Does anyone know these people or have experience dealing with them?
Yes, in my time between college & marriage, I encountered them multiple times per week in their various ministries, both attending and assisting. I was not Trad at the time and did not know the TLM existed.
Before knowing who these messages were coming from, I said, "there's only one person in the MDM that I'd give the benefit of the doubt to," and it
is this sister that is possibly receiving these messages.
I'd say that if these messages are believed at all, there are 2 conclusions I'd reach:
1) you wouldn't be able to judge the messages by the fruits of the messengers ... the MDM has been adamant about working within the N.O. structures, even cautioning me decades ago against Sedevacantism (ironic now that they themselves are Sede) ... they have also promoted "speaking in tongues" (the sort that helps no one and leaves everyone confused

) and "resting in the spirit" ... they had at one point a priest offering the TLM and regularly introducing new souls to the Tridentine Mass, but decided that he was no longer a good fit for their community and parted ways.
All of these points in #1 are old as my experience with them was 20+ years ago, however, they claim that these messages have always been given to them, predating even my experience with them, so they should have received more than a few messages about their own ministry.
2) If you're already Trad, you'd do better to read a single traditional TAN book than read 100 of these messages.
I do believe that
they think the messages are real.
Another random bit of info. One of the projects I assisted them with was a committee that worked on raising money to purchase their property. This would allow them to build and subsequently accept new vocations that they previously had no room to accommodate. 20+ years on that property now, and they're no bigger than they were then -- one priest and 3-5 mixed m/f religious. Compare that to the growth of typical Traditional communities that have a resident priest and the difference speaks for itself.