[itsme]

Batch Import shows the same behaviour: %SortTest.txt and _SortTest.txt are not imported.

Some special characters are ignored during sorting, some are considered. It is different on Win10 and Android which characters are ignored and which are considered.
The setting "Normalize Characters" ON or OFF affects not only diacritical marks but also which special characters are ignored and which are considered for sorting.

It's not the most important feature anyway. I just made some experiments with prefixes that move some songs out of the regular sort order, like those "some people put spaces at the beginning of songs to force them to the top of the list" that you mentioned before. And I'd like these prefixed songs to show up in the same sort order on Win10 and on Android.
With all the investigation that I did by now, I'm sure I'll find a workaround to achieve what I want.

Isn't a collator or a sort algorithm available that could be used for both Win10 and Android?