SR and GR are totally clear. They are unambiguous. That doesn't mean they are easy to read. Everyone who works hard enough and is smart enough to understand the math comes to the same conclusion about the nature of spacetime and gravity (and all the other consequences of the theory).
"Understandable" has multiple meanings. Something written in a language foreign to you can be totally unambiguous and understandable. Just not to you (yet).
The Bible has been translated to many languages and studied over centuries and yet everywhere is argued over. EvC is a microcosm of that.