Not an answer, but some workarounds.
I have the same problem with my Dixon/Dickson/Dixson line. I think if you put the alternate spellings in the "Other Last Name(s)" block, WikiTree should find potential matches for them too. While not ideal, there are a couple of ways to cover profiles without all the alternative spellings - go to the Surname list of the alternate spellings, sort alphabetically, and look at the individuals. If any look promising as a match, go to the bottom of the profile and initiate a match with your relative to see how they compare. One of the people I'm looking for is John Dixson/Dixon/Dickson, so I'll put his name in the "Full Name" box - x3 - to see what turns up.
If I get a match, I'll get in touch with the profile manager(s) for the other profiles to see which spelling makes most sense to them and go from there.
For my Bryan/Brien line, I have a reference that says in which generation and with which line the Brien alternative came about, so I stick with Bryan above and Brien below, with Bryan as an alternative spelling for the generation/line that adopted the Brien spelling.