pic 1:
the age of sexual maturity for human females could be as low as 3 to 4 years of age (age of youngest verified mother), sexual maturity and biological adulthood merely means the ability of the sex cells they produce to cotribute to the conception of their biological offspring with a partner through intercourse.
I think you mean "legal/cultural adulthood", but that could be anything if we put it in terms of "their species", for one, we dont have a legal/cultural age of adulthood for our species, its set at different ages for different areas and in some places theres no age for it at all! i dont think its likely to be that much different for other species who possess characteristics like ours.
pic 2:
what about anthropomorphic animals but they are normal animals that got uplifted into a species of sapient omnivorous bipedal humanoids possessing a level of potential for technological advancement that is at least similar to that of humans?
that, or what if they are humans who spliced themselves into anthros with the dna of animals?
either way, theyd be a genetically distinct species unto themselves, and would be biologically incapable of sexual reproduction with human partners, or partners of the animal side of their family tree.
you might get away with it in the case of other variants of beastfolk, such as human bodies possessed by animal spirits, or animal bodies possessed by human souls, in each of these cases its the body of a human or animal that is just transformed by magic into something possessing the characteristics of another species, if the body is dead and reanimated by possession it is technically undead and thus its reproductive viability is more questionable.
chances are, human guys who stick their dicks into real catgirls are still practicing bestiality, and will not have any fruit borne from this cross-species coupling.
shapeshifters are another thing, they are humans or animals with the ability/curse to become another species, in this case what matters is in what form they are on when fucking, id also add that if a female werewolf (wifwolf?) got knocked up by a human whilst in human form, shed lose the baby as soon as she tranformed should she shift into a more wolflike form when pregnant, due to her body becoming biologically incompatible with the fetus, so in my mind female shifters are mode-locked for the duration of their gestation, losing their ability to change forms might be a clue for a femshifter that shes gotten preggers.
man, i am overthinking this a bit too much.