Welcome to the forum!
I wouldn't worry about it unless maybe you have a criminal record.
IMBRA compliance is mostly a requirement for the agency, not the customer or the girls. Whether or not the agency even falls under the jurisdiction of IMBRA is something for them to worry about and is beyond your control.
In the event that you were to someday petition the young lady for a U.S. fiancée or K-visa, you would have to disclose the fact that you met through an agency and possibly provide any pertinent criminal background information.
If you were to marry her overseas and then petition her for a CR-1/SR-1 spouse visa, then IMBRA would not apply you anyway.
Is that outfit based in Australia?