You have two issues going on:
1) The Hungarian emails don't send
2) Some products can be purchased and others can't.

For #1, could you post your current admin settings for Localization->Languages (make sure to obsure/edit-out any account-specific filepath information).

For #2, I think that you will need to do what DrByte and others suggested in your other thread, i.e. you'll need to review each of the Hungarian product descriptions and re-save the information now that the admin is setup to use utf-8 encoding. It seems that the information is stored in non-UTF-8 format for some of the products.