This is a won't fix, I believe, although I'm going to punt this to @ssastry for comment when he returns from sabbatical. We shouldn't really be emitting fallback text at all, and to the extent that we do it is desirable that it is consistent for machine-readability of citation markup. No humans should see that.

If there is some way that fallback text is being shown to human readers, then we should treat that as a bug and fix it.

There's still space for discussion, but I'd like to point out that the parser emits localized text, and in particular the legacy Cite parser emits footnote marker numbers as literal strings. These numbers can be customized by on-wiki overrides according to group name, for example see https://en.wikipedia.org/wiki/MediaWiki:Cite_link_label_group-lower-greek . What's the benefit of having Parsoid use CSS counter reset for every footnote? This is a mechanism that I'm planning to remove entirely, so it would be great to figure out a consistent way forward.

Also: I've created a parent task to reflect my team's further plans, let's please shift any discussion here instead: T370027