Hi,
MaxDB does not offer any elaborate audit logging.
For any ddl related table changes, you can query as sysdba user the internal table 'sysddlhistory'.
Regarding the 'dbm.prt' log file size, just increase that size via the 'dbmcli ... dbm_protfilesize <size> <unit>' command - arguably not very obvious, I have to admit...
Thorsten