너무 is "too"

많이 can be "very" sometimes when you translate it but in Korean it's normal to use it like this, just as you could use 아주 instead.

If you think about it, even in English something that is much expensive is also very expensive

You should flag it. Flagging is the tool that helps the development team create alternative acceptable translations.

No its right. I guess what they accept is really strict.

"The tasty beef is very expensive." is now accepted.

I would like to know this too cause i also used tasty

Because they are talking about a specific meat, so you would use the in English.

Beef is uncountable.

Delicious beef is too expensive.