forum #9039 discusses cum_inside being aliased to cum_in_pussy, and further addressed internal_cumshot remaining separate, though its wiki still aligns itself with the former, implicated tags.
However, to my knowledge, there is not a tag for "ejaculation while penetrating", as compared to cum_while_penetrated, with the latter using "cum" as a verb, as my impression of "cum inside" is (read, "to ejaculate while penetrative").
At any rate, these tags could use some clean-up, but I wouldn't know how far would be agreeable. To align itself better with other tags, I'd say to alias or mass edit internal_cumshot to internal_ejaculation, but this may lead to intuitive repurposing as the "cum while penetrating" ("internal" here being location rather than perspective), with a different tag for crossectional (but if this route, may be cleaner to mass edit internal_cumshot to that tag, then manually applying internal_ejaculation). But for cum_inside, that I feel less sorted.