I was looking into Parsimonious and CORRY's Factory again, and I thought 'So Kate did quick-and-dirty job to make those dresses buyable formal clothes'.
If you look into CORRY's Factory, you'll find CORRY has normal version and formal version of the same dress meshes. They're like:

B52h = F50f
B52i = F50g
b476 = F50a
b487 = F50b
b488 = F50c
b489 = F50d

Instead of using proper formalwear meshes, Kate simply renamed 'b' to 'f'. It works of course. But I wonder if it could introduce some conflict with other formalwear meshes.

Renaming B to F is so normal that Woobsha has a tutorial explaining how to do it, for those who want to change the category of an outfit. As long as the internal file specifications are also changed, and as long as the numbers aren't the same as any other numbers already present, it works fine.

Kate knows what she's doing; you can trust her.

I've used Parsimonious clothing all the time, so I never worried.