Illyrian (with perhaps painful transparency) is designed to resemble —
Middle Dutch — < gh > as a possible spelling of /g/, merger of masculine and feminine singular definite articles to tha
Dutch — use of < ij >, which can represent either /i:/ or /ɛi/, < sch > for /ʃ/
French, Frisian — circumflex marks long vowels â ê î ô û, also < eu, ou > for /œ: u:/, lots of unpronounced written final consonants, merger of /ai ei/ to /ɛː/
Middle French — use of eû as a variant of û to spell /y:/, cf. Mod. Fr. j'ai eu, nous eûmes, at the end of a word, /i/ is generally written < y >
English — erratic application of sound changes, doublets of the same word having come to mean different things (clocke "bell" and cloche "cloak") and echt (non-gendered third-person emphatic form)); slightly nuanced synonyms (including blesse, fleure, floure, blute, flute, all meaning roughly "flower"); large numbers of loanwords which have become everyday vocabulary — cf. lud, lachert, sorcelleria, littératura, cloche, horologe; final < e >, often descended from /ə ər/ has come to be pronounced /a/; changing a lot of vowels to /ɛ/ because it makes me think of highly affected speech.
Scots — use of syllable-final < ch > for what was once /x/, and what is now either unpronounced or non-syllabic /i/ in certain cases
Italian — lots of words ending in /a/ and /ia/, both of Latinate and non-Latinate origin, loss of neuter gender
Russian and Hungarian — provide vocabulary such as imia, Majarsagh, almos, theve (lit. "given name", "Hungary", "slumber", "tree") and others which appear to come from nowhere
"Think only of the past as its remembrance gives you pleasure."
-Jane Austen, Pride and Prejudice