They probably add nikkud to help when there's a possible double meaning without it: שם can either be "shem" = name or "sham" = there. יפה can be "yaffa" = beautiful (feminine) or "yaffe" = beautiful (masculine).
I get that, but they shouldn't require the nikkud in answers. I don't know when they're going to require it, and I've gotten things marked wrong because I wrote אני רוצה and they wanted אני רוצֶה
As far as I know it's not required - it should be accepted or at least write "almost correct" or something like that. I suggest reporting it to the admins if it happens again.
I've already missed some answers because I didn't put a gender-marking vowel in the sentence. These poorly constructed questions appear at the lower levels of the program.
They should not be required normally. When they are, it's an oversight and should be reported.
If you're on Mac, you can very easily go to your keyboard settings (System Preferences > Keyboard > Input Sources) and select 'Biblical Hebrew – SIL'. This keyboard input has nikkud built in :)
I encountered at least two versions of pronounciation of feminine יפה - 'yaffa' and 'yefá'. Is any of them more correct in everyday speech?