Well, it's possible, although it's a lot less convenient than before Select2 was upgraded: now, instead of double-clicking on a token value to change it, you have to bring it to the front of the list, then hit "delete", and the value becomes editable.

Indeed. That's not intuitive at all. And it leads to changing the order of values.

Well, you can always change the order back, but the rest is true.

Change 670442 had a related patch set uploaded (by Sahajsk; owner: Sahajsk):
[mediawiki/extensions/PageForms@master] Enable double-click to edit tokens

https://gerrit.wikimedia.org/r/670442

Change 670442 merged by jenkins-bot:
[mediawiki/extensions/PageForms@master] Enable double-click to edit tokens

https://gerrit.wikimedia.org/r/670442

Well, double-clicking on tokens now "works" - although it doesn't work as well as it did before the Select2 upgrade of a year ago. Now, double-clicking on a token moves it to the end of the list, and makes it editable - whereas before, double-clicking used to keep values where they were, while making them editable. So I'm not sure whether this bug should be considered fixed, although this is at least a partial fix.

I tested it on my side. Thanks for the patch.

Sometimes double-clicking a token, with the intention of editing it, results in the removal of a token, which isn't really helpful.

I don't know yet if this behaviour is specific to longer values (40+ character values are not uncommon for me), token fields that don't allow for more than one token, or maybe to token fields in multiple-instance templates.