Warp names on signs are case sensitive even when settings.caseSensitiveWarpNames config option is false.

If I remember correctly, MyWarp attempts to set the correct case of a warp name on the sign upon creation.

Could you briefly describe, why this behaviour is still problematic? Was the warp deleted and than recreated using a different case or...?

Seems like the warp is creating like it was typed without recreating. Players can use /warp WarpName typed in any case, but if they want to add the warp sign, they must use the valid case as listed in /warp info WarpName.

Paperspigot build 1415 (MC: 1.12.2)
Plugin version 3.0-SNAPSHOT+jenkins-b192.git-91cdc14a6b
config.yml https://pastebin.com/raw/tGp6QWxB

Should be fixed in the latest devBuild.

However, please note that if there are (for some reason) two warps with the same name in different case (e.g. TEST and test) signs will not work for either of them, regardless of the sign's text.