I Think You guy's are over thinking Lifespan problems. At least not in the right direction.
With the Multiverse on "Hold" A lot of The "Refuge's" Life Spans are also on hold, as they are tied to the process of the individuals Home 'Verse.
Although it might be a while before anyone notices that they are not aging, and asks about it.
So, if some on brings up a possible lifespan problem to Washu, at least have her go through the process of asking if individual wants the problem to be fixed.
With the Multiverse on "Hold" A lot of The "Refuge's" Life Spans are also on hold, as they are tied to the process of the individuals Home 'Verse.
Although it might be a while before anyone notices that they are not aging, and asks about it.
So, if some on brings up a possible lifespan problem to Washu, at least have her go through the process of asking if individual wants the problem to be fixed.