Legion > The comments I promised. They are verbose indeed - my apologies to everybody not interested in the subject...
(1) All the published descriptions of the Isles langs are very sketchy. It is clear to me that all these conlangs must be fleshed out. The migrations of Isles-speaking peoples cover a huge region of great importance: the natural bridge connecting three big continents; they happened during a very important period when the earliest states were formed and trade routes established. For me, this means that sooner or later we'll need a detailed history for each part of the region and for the migrations of each of the Isles-speaking groups.
And for each period we'll need the exact forms of tons of words (toponymy, people's names, native terms for social institutions, etc.). In other words, rather detailed internal histories for the languages (not confining to just phonetics, but covering also productive derivation, rearrangements in PoS systems, productive alternations, etc. - in short, complete historical grammars).
The above was an attempt to explain that the question I was trying to answer for each of my "issues" wasn't just "Why not?", but rather "Is one human life long enough to compose a historical grammar explicating this in reasonable detail?" :)
(2) I perceived the published conlangs of the Isles stock, including PI, as not subject to any revisions. That is, stuff and detail can be added but what is clearly stated in the available descriptions must remain valid. I still consider this a priority, perhaps even the main priority, especially for languages that have been already used as sources of loans, toponyms, etc.
I know that some items in my list of "issues", maybe even all of them, can be forced into some complicate artificial scenarios. I spent a lot of time trying to figure out how this or that feature could be realistically obtained in a direct descendant of "Ran's PI". But as the oddities accumulated - derivation by metatony (Máotatšàlì), adjectives agreeing in case-number-declension class (Mûtsipsa'), an alternative nominative marker (Ppãrwak), postpositive adjectives (nearly everywhere), VSO (Máotatšàlì again) - etc. etc., I had the ever strengthening feeling that I was doing something wrong. At some point I realized that my internal dialogue on these subjects resembled the anecdote: "My wife slipped and fell onto the knife." - "Sixteen times?".
Also, I realized that it was stupid to ignore
Ran's own words that seem to imply that he perceived his description as relating to just one dialect, while some of the daughter languages could descend from somewhat different varieties of the protolanguage.
But then these dialects of "late PI" must have had a common ancestor, some "Ultimate PI"; many of its features can be in principle discovered via a reassessment of the features found in the daughter languages. In other words, with every non-trivial feature in a daughter there are two options: it can either be forced into a scenario explaining the details of its development based on "Ran's PI" - or be declared an archaism, pointing to a yet undocumented feature of "Ultimate PI".
The "issues" in my tentative list are (reflexes of) such potential archaisms.
(3) I was looking at Naxuutayi already with this new perspective in my mind.
For example, why ignore the different usage of cases with postpositions while the data from the sister languages (Mûtsipsa' in particular) seem to suggest that "the dialects of PI" already varied in this point?
(4) On the Naxuutayi cases.
Latin is hardly a valid example of instrumental semantically shifting to ablative: the "ablative" of Latin results from a simplification of an earlier case system involving a merger of two or more cases that used to be distinct in the ancestral language. Had PI had a distinct ablative merging with the instrumental through phonetic change plus analogy, the parallel with Latin would work, but this would be a major revision of PI.
OTOH a semantic development like ablative -> instrumental is easy; in fact the use of the PI instrumental with postpositions looks like a rudiment implying that ablative was the original function of this case.
Similarly, allative -> dative/benefactive seems to be much easier than the other way round.
Dative -> genitive is OK, but further shift to meanings like "origin" or 'composed of' is hardly compatible with the original functions of the PI dative. That is, there are several changes: (a) dative used as genitive, (b) dative in its original functions is supplanted with benefactive, (c) the new genitive expands its use to "origin" etc.; each time the next change can start only when the previous one is complete. (Note that this case is listed among "multistep scenarios" rather than "issues".)
The use of instrumental as comitative is not easy to derive from its functions in PI; a development like instrumental -> comitative is difficult, and uniting these two functions in natlangs is better explained by a reverse development (cf. the instrumental use of prepositions in European langs, which seems to be invariably secondary to a "comitative" one). But this may be irrelevant if the postpositions in question are themselves recent conversions from nouns or verbs (e. g. construed like
accompanied by in English, with instrumental for
by). Basically the same works for accusative as perlative and for benefactive as illative.
(5) The anaphoric pronouns: indeed, there is a possible development like 'act of hiding' -> 'what is hidden' -> '(that) hidden one'; however, it is not clear if such shifts were productive and how they could affect the whole derivational system. That is, while not being too difficult per se, such a development seems to be fraught with complications whose scope may be difficult to assess. OTOH the pronouns could simply reflect a different derivation pattern not preserved in "Ran's PI".
(6) Numerals: an explanation is needed of how the case endings were dropped and the order of the components was changed. Cf. the construction required in "Ran's PI":
tayq kákakatah nami huyi sá kákatahi huyi katahi huyi sáyi. Since constructions without case endings are also found in sister languages, it is easier to suppose that numerals were not obligatorily construed the same way in all dialects of PI.
(7) The serial form of verb: sorry, indeed what I said wasn't especially clear :(
Sure, serial constructions can easily originate from something like "X, then Y, then Z". However, the Naxuutayi marker is a suffix, i. e. implies a rearrangement like "X-then // Y-then // Z". IMHO this is not easy at all, no matter how simple it may look at first glance; it is much easier to postulate a somewhat different (or broader) usage of the word which is described as simply a conjunction in "Ran's PI".
(8) The prefixes for perfective/imperfective: after thinking a bit, I admit that a development like "eating-sing" -> "exhausting-sing" -> "completely-sing" -> "PERFECTIVE-sing" is rather straightforward.
And what is your scenario for 'do' -> imperfective?
(9) A completely different topic: if Thokyunèhotà remains as a "once important language", maybe Thumapahìthì, the old name for the archipelago, remains valid as well? (It appears on some maps and has been used in the discussions many times.)
Do you have any description of Thokyunèhotà, maybe a tentative one?
(10) No, I wouldn't suggest Thokyunèhotà as the language of the "potential dominant power" of ca. -1000 YP: that would mean that its speakers gained influence even faster than my dense scenario proposes for the Sošunami :)
I think it could be just a language of a big city in the northern part of the archipelago, actively trading with the continent; then at some point it could be known to the big nations better than Naxuutayi.
Rather, I'd suggest that the language of the "potential dominant power" was of the Peninsular stock: that seems to agree better with a related one dominating the adjacent area on the continent.