Looking at the spamfilter_users policy_id settings in the sql tables, it appears to me that "Normal" is a setting of 5 and "Permissive" is a setting of 7.
I reckon you could try a SQL statement like:
UPDATE `dbispconfig`.`spamfilter_users` SET `policy_id` = '7' WHERE `spamfilter_users`.`policy_id` = 5;
Then try a mailbox resync from ispconfig interface.
Would like to know myself from a developer if the above is feasible!