Run the following SEDE query: https://data.stackexchange.com/japanese/query/178382.
All the tags except
たい-form get auto-linkified. These happen to also be the only four tags that contain characters outside the standard set of allowed characters
[a-z 0-9 + # - .]. It would be nice if these would auto-linkify too.
(I imagine this is even more applicable for other language sites like Russian - if you rerun the query for Russian, you find that well over half the tags don't linkify because they contain Cyrillic characters.)