Pac-Man-
As far as enforcing the ban goes- the guys would happily say “I’m sorry but your credentials have been suspended/ revoked. Unfortunately I can’t take any names from you or I’ll be going against Daas Torah”.
Hopefully the girls and their parents will see that it is in their long term best interest to avoid dealing with any Shadchanim who violate the policies.
Concerning the fines- my father has a novel approach for the illegal immigration problem that he will implement as soon as he is elected president. The Pepper Administration will provide a large amount of cash to the leaders of each country every year- say $10,000,000. Every time an illegal immigrant comes in $1,000 is deducted plus all expences (hospital, jail…). Let’s see how fast the leaders stop their citizens from skipping the border.
There are many cities that offer cash incentives to shadchannim to find husbands for the single girls in their communities. If one doesn’t want to pay the fine then just hold it from their next bonus. (Or there could be a system of having them be fully bonded, like your plumber and electrician, before being certified.)
I agree it’s easier said than done, but there are painful steps that have to be taken.