I reckon moral views can change diets but not tastes. They are both fantastic, beef is better, tomatoes are solid, and I will gorge myself on all three then smoke a cigarette.
I understand the use of -aĵ- for specifying meat from those animals - but, for example, trinkaĵo (used later in the course) is the word for beverages, and not "drink meat", and manĝaĵo means "food" and not "meal meat" (whatever that would mean). I just think Duo should give us the specific meaning of the suffixes, instead of crude examples. I don't see "the suffix -aĵ- specifies food" anywhere in the supporting article, it just says so for meat - and proceeds to use it in exercises where it is not in that context.
I believe it means "a concrete example of something". For example (with apologies I'm not on a computer with diacritics), trinkajxo = beverage in general, bovajxo means beef (beef meat), etc.
There are times when a word can be translated two different ways depending on its meaning. For example, painting can mean the act of painting, or the thing you hang on the wall. Pentrado means the act of painting, pentrajxo means the thing you hang on a wall. Ajxo on its own would mean a concrete thing.
This help at all?
There exists keyboards for phones: iOS: https://itunes.apple.com/us/app/esperanta-klavaro/id957192189?mt=8 (not sure if it works, I have Android :P) Android: https://play.google.com/store/apps/details?id=com.google.android.inputmethod.latin (Esperanto is an available language)
tastier already implies that pork has a better taste than beef, and the sentence is saying pork tastes better than beef, so you would just translate the sentence as "pork is tastier than beef". If you wanted to say "much tastier", I believe you would say "multe pli bongusta". Don't quote me if I'm wrong.