Board Thread:Support Requests - Getting Technical/@comment-27049154-20190701125713/@comment-1038387-20190701134034

The Variables extension is 1.29+, whereas Fandom is on heavily forked 1.19, so it's probably not an option. An upgrade to something newer is in the works, but will take a while. You could ask them to enable it on your wiki via Special:Contact, but there's no guarantee they'll honor that request.