What's the importance of complement and relative clauses?

[Turama]

So firstly, a complement clause is the clause that is mostly expressed with that in English. For example: I saw, that he slept. Headless relative clauses would be relative clauses but without a head, obviously. Something like the sleeping one though one is used as a dummy head in this case, some other languages would use just the sleeping, like Latin for example.

The sentence ilapim phaiatasa could either mean I saw, that he sleeps or I saw the sleeping one. However how important is this destinction though? I mean of course it's my conlang but how realistic is that cross-linguistically? Who knows maybe it's a very important feature cross linguistically and I just remove it.

Before I changed that the second meaning was expressed through the use of the prefix tzha-, so that the sentence would be: itzhalapim phaiatasa I saw the sleeping one.

PS: I believe I heard that some north american languages do the same. I think it was Navajo, but I'm not sure.

[Salmoneus]

"I don't like the sleeping one" is not the same as "I don't like that he sleeps".

[vec]

I don't like the one who sleeps and I don't like the sleeping one are roughly equivalent, relative/participial, respectively.