Whoever is in control of this team, needs to pick one, and stick with it. Hiring enterprise developers if you really want your MVP out the door yesterday is asking for trouble.

It also leads me to believe your product currently has a dearth of tests. Most of the bugs that are generated from refactoring should be caught by automated tests. Until you have tests, you shouldn’t refactor (always write a test first).

If your product is too difficult to test, the enterprise crowd may have a point and the initial (and further) architectural decisions have been wrong, and this suggests a lack of senior engineers.

Last point, if your abstractions are making it more difficult to test, then the abstractions are almost certainly wrong.