I ignored oldwikisource rules, and I uploaded there some Index pages from a multilingual magazine collecting articles in French, German, Italian with English summaries, one of them is https://wikisource.org/wiki/Index:Labi_1997.djvu
The try is to test oldwikisource features and issues and to to import there and test some useful templates (in Lua too) and editing scripts to expose there to wikisource community and possibily to begin to build a set of shared ideas.
My proposal is, to remove the prohibition to upload there multilingual works, even if their language is covered by a specific project; to encourage users to upload into oldwikisource any multilingual work; to create a specific interwiki code (mul:) to allow links to them; and to encourage any user to import into oldwikisource best ideas of their favourite project, and to discuss them after comparison with other functionally similar solutions.
Can be, that this would decrease a little bit the deep, growing difference in styles, scripts, templates among wikisource projects.
If wikisource community thinks that I've to remove my uploads since I'm going into a wrong way and disrupting something that needs to be saved, please tell me and I'll do.
Alex brollo