The caveats are well-known and well-publicized. If you want Turkic-specific case mapping behavior, you really have to use the Turkic-specific case mapping tables.
I already use this Turkic specific mappings. They have no problems at all if I use "C" + "T".
There is also no problem in the simple mappings: "C" + "S".
The problems come when I use the non-Turkic full mappings: "C" + "F".
So reread what I said, and now just consider the existing CaseFolding rules, when all "T" rules are removed, and only "C" (common) and "F" (Full) mappings are used...
It still comes back to what Doug said: The default rules make sense for most languages, while in order to make sense for Turkic languages, you must use special rules for them. There is no way around it - it comes from the fact that they use the same letters in a different way.
markus
