Yeah. It seems arc ending isn't her strongest side as writer.
Bur I think it is a problem with a lot of writers, really.
Endings are the toughest part of writing. Very hard to pull off...
Character-balance aside, when I critique a book, it's always story first. The fault in R&G's ending was that it probably needed just 4 issues instead of 5, and Dr Brand should've been the main antagonist, in fact maybe not have Lavish at all and give her abilities to Dr Brand because she had more panel-time and was a more interesting character than Lavish herself...instead of just being a golem.
With MMX, it was a big story, action-packed, character-driven, Xandra and Cerise were very good supporting characters, Deadpool was a good guest star as was the Technet and Imperial Guard, Deathbird is (arguably) in the top 10 most prominent X-Men villains, she was a good choice. I loved the scope of it, however the ending felt like an ending to a 2nd act. It probably needed another 2 issues to give it a better ending rather than finishing it off with just an illusion. It needed a better final showdown with Deathbird and co.
That said, I certainly had my money's worth in both arcs. A lot of fun.