It's a critical feature if we've seen them before.
Yes. No. Maybe? If you're telling me the current April is the same as the April in "The Counter-Clock Incident", I'd say no. They aren't the same character. If it is a new version of the character, fire away.
And, if it was April alone, I'd probably squint as best as I could. On top of everything else? I just treat it as a multiverse.