After some tests I realised when using mltvndr extension, and processing a withdrawal, the gateway fees (not the commissions) are not taken into account. The vndr rceives only the amount minus the commission.
On backend side the same, on commissions, the gateway fees are not taken into account in net earning. And on wallts transactions the same.
Unfortunately I have not yet had the time to work on this. I generally do not give ETAs on new developments, as it is really hard for me to know when I will be able to find the time to work on stuff. But I do make a note to post a notice to the same thread, once a relevant release is made.