Two problems with the word endngs: A) Samia is a feminine proper noun, and as such, doesn't receive a final -n (as a dipartite noun). And it's in the nominative, so it takes an -u, not an -i. Saamiiya(-tu). And B) Jayyida(-tun) is in the nominative, not the accusative, so it takes -un, not -an.
Yes, I think that's right -- and to add to some related things said elsewhere in the discussion forum, it's not just Quranic recitation where people take meticulous care with those endings, but also often in poetry recitation, and occasionally with network news readers, etc. In informal MSA usually they're omitted, and in regional dialects pretty much always, except maybe when citing stock phrases from formal Arabic. As this course gets further developed, hopefully some thorough explanations will find their way into "Hints and Notes" files. To use some traditional grammar terminology, those endings are "markers" of "case" and "definiteness", and they have counterparts in assorted other languages.
Because the course makers wanted to make a mishmash of Standard Arabic (where the endings are used) and the vernaculars (in which they're generally only used in set expressions), so they apparently chose that the version of Arabic they've created wasn't going to have case endings. But the computer voice wasn't made by them, unfortunately, so it keeps adding in its own endings. Needless to say, computers aren't the best at grammar.
Best thing to do would be to report it to Duolingo as a bug so hopefully they will fix it. You can report it here: https://support.duolingo.com/hc/en-us/requests/new. I'll report it as well.
Problems with the pronunciation is not a bug in the Duolingo system that I imagine tech support could or would take care of. It is a problem with the TTS system that is being used to read the Arabic script. We should report pronunciation problems at the bottom of the page were we do the exercises. I'm losing faith that pronunciation problems are going to be corrected, though.
T in (t)un, (an) and (t)in is part of the feminin form. Pronounced only in certain positions. The (t)un, (an) and (t)in are case endings, which do not appear when words are presented as a single word, but they do appear in a sentence, depending on wheather the noun takes nominative, accusative or oblique case. This is something that happans only in MSA, not in dialects. Correct me if I'm wrong. And I don't think the case ending is pronounced at the end of a sentence. The problem is that the automatic voice does not seem to be consistent in this and it seems to mix between (t)un and (t)an. Haven't heard (t)in year. This is how I have understood these matters. I'm not an expert, so I welcome experts to correct me if I'm wrong.