I have submitted several tag wiki edit suggestions, which have been approved.
From a quick look at my revisions history, there's compression, sales, energy-efficiency, xwindow-x10, xwindow-x11, 8088, punched-cards and ibm-pc. Several of these have also seen a fair amount of use, and several (but I don't think all of them) are ones I created. (A rule of thumb for me is to never create a new tag if I can't think of a reasonable tag wiki excerpt that summarizes its intended use. Of course, I try to remember to come back after the edit is approved, if applicable, to actually propose the tag wiki excerpt too!)
Certainly ibm-pc is an old one by now; I created that one by adding it to a question of my own a year ago, and the initial tag wiki was approved around that same time.
Even so, on my profile, Research Assistant ("edit 50 tag wikis") still shows the progress as 0/50.
What's up with that?