For what it’s worth, this is the first time I heard tags have ‘sections’. I’d just been typing into the box and getting autocomplete! I see now there’s a whole menu under a button-that-doesn’t-look-like-a-button (flat design taken too far!). Can’t be the only one in this situation who took it as a neutral tag.
With that in mind, I agree that the tag itself is unsatisfactory, at least if assumed to be adult without other tags, some of which do not exist as defaults. For example, ‘babyfur’ is a normally non-sexual form of ‘ageplay’ (by itself at least; babyfurs or their players may also engage in sexual roleplay).
As for ‘ageplay’ itself: these are tags applied to characters, not players. ‘ageplay’ as a preference in theory means the character is interested in adult characters - maybe themselves - pretending to be (usually) underage. Some may assume it is a player preference for underage characters which will not always be correct.
There could be a (General) character attribute ‘underage’ which would more clearly specify the situation by its presence or absence (e.g. Kai is ‘small’, open to ‘ageplay’ - hey, free candy! - but isn’t ‘underage’, any more than the average kobold). Though perhaps it is enough that some characters specify their age (insert sidebar about how some species canonically live ten hours…).
It doesn’t help that, alphabetically, ‘ageplay’ may be the first tag you see unless buried under other custom ones; and if you customize ‘ageplay’ to clarify, it pops back up.