Hi @astrava,
This is because you ran the following as root from an interactive shell when testing:
# /opt/kaltura/sphinx/bin/searchd --config /usr/local/sphinx/etc/sphinx.conf
So the files under /opt/kaltura/sphinx were created with root.root 600 and now when the init script tries to run searchd as the kaltura user, it cannot write there.
I suggest you:
# rm $BASE_DIR/sphinx/kaltura_* $LOG_DIR/sphinx/data/binlog.*
and rerun the configure script.