I feel like they should rather be looking at women or should stop infantizising them if they hopefully already are doing so..
I concur. This sentence could def. benefit from a revision. For example, "La KNABoj vidas la...KNABINoj"
"Vidas" means they just happen to see them, it does not mean "watching" or intentionally "looking at". So this sentence is perfectly innocent.
I think it's more of a reflection on us than Duolingo if we're assuming paedophilia because a man can see a girl, and the girl is pretty.
Because endings for adjectives and nouns should match.
From the Tips and Notes for the Accusative skill:
Note that an adjective modifying a direct object would also receive the -n ending. Thus, Virino kisas belan viron. would mean "A woman kisses a handsome man." As explained above, we could also phrase this sentence as Belan viron kisas virino, which would still mean the same thing with more emphasis on the good-looking man.