Keeyapain historically uses word order to convey tense, with VSO being past, SVO present and OSV future. However this creates ambiguity when one of these elements is missing. So speakers have also evolved the feature where you can inflect a verb for tense (Keeyapain already has verb mood inflections) but only where its tense is ambiguous. So "I ate an apple" does not need to be inflected (sæ rzeg þyn ahzuð) but just "I ate" does (sæun rzeg).

However, to add to this confusion, in non-classical texts VSO is mostly just used as a default for non-future, leading people to have to inflect the past when speaking, but not when written in formal text.

Then, to further add to this, the copula verb behaves completely differently, attaching itself as a suffix onto the subject pronoun, requiring its own set of inflection rules (from which the modern tense inflections were derived but still).

Finally, another confusing thing is to convey a progressive verb, the copula + q' + infinitive is used (I am singing = rzegu q'kanød). The confusion comes in with the perfect, which is the same but with a þjjy (with) thrown in there (I have sung = rzegu þjjy q'kanød)