A real choice -- yes, that would be nice. I am nominally a member of the Democratic Party and yet I completely abominate it, in its present incarnation. But that doesn't mean I am going to become a Republican.
Let's review the Professio fidei Tridentina. It's actually gotten a bit longer since but ....
I think what is highlighted in yellow points more towards areas of difference in emphasis and terminology. I don't see these as 'make or break' issues, where compromise is just plain impossible.
The red? That's another story entirely. And who stands precisely where ... now?