The activity rule form will be stored in the pr4_rule which will be in XML format, but the generated java FUA will be stored in the pr4_rule_sysgen table. So to confirm you the created activity rule will be stored in the pr4_rule table only.
The pr_other table is the default destination for saved instances that belong to a class that is not mapped to any other table. To access the pr_other table, the system uses the catalog and schema specified for the pr4_base table as identified in the databases/baseTable/catalog and databases/baseTable/schema entries in the prconfig.xmlfile or Dynamic System Settings.
Each time an object is saved to the pr_other table, the system adds a PEGA0041 alert to the alert log.