With "beszelni" ~to speak and "beszelgetni" ~to talk, I suggested "who spoke in the restaurant. Acceptable ?
Yes, it is.
I ran into the same thing and reported it.
What does "etteremben" mean in this context?
Are there few forms of "in the PLACE" for example "szallodabon"?
I want to know if there is also vowel harmony in the descriped situations?
The suffix you're looking for is -ban/-ben and means "inside of" the thing.
étteremben = étterem (restaurant) + ben (in)
There are two versions of this, -ban and -ben, and indeed usage depends on vowel harmony. Your example "in the hotel" would be "szállodában".
Dining hall should also be accepted. Will I get any feedback for my comments?
I'm not sure I would call a dining hall étterem. Étkező seems more fitting for that.
And it's likely that you won't get feedback for many of your comments. It's just that nobody happens to read them soon enough. Sorry for that.
you should use the report button, but not for this one - étterem definietly means restaurant, and not dining hall :) not logical, but that's how it is.
Ooh sudden past tense. We have not learned tenses yet.