Hi,This should not be a blocking issue if we disregard {T206426} which I do not think we should consider implementing except for possibly allowing sitelinks to be prefixed (//a la// `Special:MyLanguage/`) on their way to their target wiki. See my comment on that task.
As such, I believe we should handle mul.ws as a `oldwikisource` multilingual wiki in the same fashion we handle other multilingual wikis like: `meta`, `mediawiki`, `commons`, `species`, `wikimania`, `wikidata`, etc.
If we want to renamed `oldwikisource` across the board (leaving some backwards compatibility for old interwiki links), that is probably a good idea too. I recommend `mulwikisource`. However, that should not block editors from manipulating Wikidata sitelinks for this wiki (as per Jarekt's earlier comment, apparently 11 Wikidata items already have such sitelinks but they do not display properly on Wikidata entity pages and normal editors cannot otherwise manipulate them).
If we do this and handle this wiki the same as other multilingual wikis this has some implications:
- this wiki will likely show up on Wikidata entity pages under "Other sites" and not "Wikisource" (we could change the label to "Wikisource monolingual" or similar)
- if we are on a non-wikisource monolingual site (like English Wikipedia), we need to consider how toolbar interwiki links should show when we have multiple wikisource links: one to multilingual Wikisource and one to monolingual Wikisource in the current language (e.g., English Wikisource).
- if we are on a monolingual Wikisource site the (e.g., English Wikisource), the toolbar interwiki links should show both other sister projects links in the current language (e.g., English Wikipedia) as well as the multilingual wiki links such as multilingual Wikisource.
- if we are on a multilingual wiki site how should the toolbar interwiki links look when there is a sitelink to multilingual Wikisource and a monolingual Wikisource in the same language as the current wiki. Potentially two Wikisource links need to be considered. Interwiki links to/from https://wikisource.org (multilingual Wikisource) are not managed by Wikidata. recommend we specify multilingual Wikisource and then just Wikisource as we currently are doing.
For the most part this is how standalone multilingual wikis are already handled so the number of cases that needs consideration and possible changes should be minimal.