Translation:This question is difficult.
I've noticed a few sentences where Duolingo includes 很 in Chinese but doesn't include "very" in the English translation. Does that come across as strange to anyone else, or is this normal?
Chinese adjectives normally cannot function as a predicate (verb) without a so-called “adverb of degree” (very, really, completely etc.). So you cannot say *这个问题难, you need to add an adverb of degree.¹ 很 is the weakest of those, more a placeholder than anything else. It only becomes equivalent to English “very” when it’s emphasised, otherwise it should not be translated at all.
¹ Technically you can say 这个问题难, but only under certain special circumstances, so I’ll ignore those for the moment and just talk about the default case ;)
The Chinese to English translations are inconsistent and often problematic. It is very frustrating.
Probably because in Chinese the adjective 难 is in the predicate, not before the noun.