Walter Meyer wrote concerning Bacewicz:

>I assume the composer's name is coincidental and not a German/Slavic
>version of "Violason" from "Bratsche" (viola) and "wicz" (a Slavic proper
>name suffix corresponding to our "son")!

It has nothing to do with Bratsche.  And there is no "r" in Bacewicz.
Besides, surely you know that Bratsche comes from "[viola da] braccio".

The family was Lithuanian and some used the name Bacevicius, but this
seems to be actually a Lithuanized form of a Polish name.

-Margaret Mikulska