Fixed with Update on 22th september
Referring to Customize the layout for symbols - Keyboard - latest
Using SYM s on custom symbol page crashes often if Umlaut "�" (not math beta) is put on position 's' on pkb. It also switches crudely when using SYM SHIFT the � turns to SS on vkb symbol display but doesn't switch back to � on anothe SHIFT. Perhaps this is the part where the keyboard crashes sometimes.