definitely tell you that without loose address matching that matches
 user expectations, whatever they are, your customers will hate you and
 decide that your system is unusable.

Totally.

My point was intended to be helpful in pointing out where you might find data
to extend loose matching.

I've been wondering if it's worth spinning up an IRTF

Typo for IETF, I take it.

group to try and collect advice on loose matching and (sort of its inverse) son-of-PRECIS
assigning user names that allow characters that users expect, but that won't collide with variants or if non-speakers misenter them as homographs or near homographs.

Can you get enough bodies to join an IETF working group for 2-3 years?

Without that, nothing will happen in the i18n arena.

A./

PS: would be great if some issue like this could attract enough participants to deal with these kinds of issues.