I finally decided to try if Jolla automounts my sd card. The original release automounted my card (SanDisk 64GB as btrfs) and media player found music files. After the first update i "lost" my card and resorted to a fixed mount configuration. Today i went through this thread and the modifications to mount-sd.sh were s simple enough so i modified it with Jolla's vi. (I made a backup of the original first). Worked great. Then I made symlink from music-directory on sdcard as /home/nemo/sdmusic. After reboot the player finds my ogg files again.

Thanks to you all for great advices. Later this week I might have some small piece of information to share.