Long prefixes and short prefixes link to same language projects in english projects, for example in enwiki:

[[wikisource:example]] and [[s:example]] link to english wikisource

But in non-english projects, Long prefixes and short prefixes link to different language projects, for example in zhwiki:
[[wikisource:example]] link to english wikisource, [[s:example]] link to chinese wikisource. And see test case in zhwiki: https://zh.wikipedia.org/wiki/User:Shizhao/T218757

For non-English projects, there is a lot of confusion in the use.