I reflashed - all went good without any errors. After installing CSSU testing (thumb version) my filesystem broke again (fortunately mmcblk0p1 so easy to fix doing chkdsk from windows) . I was suspecting that my internal memory wear off but I have no IO errors in dmesg which indicates that there is something in CSSU that breaks my filesystem. I was using CSSU stable for some time and never experienced filesystem errors so it may be related to some changes in testing.

System sounds are fine now, so filesystem corruption was the reason rather than pulse audio.