Do you believe all of the NT books were written in Hebrew?
Re this, I heard someone make a point that I thought was good: when folks invoke hypothetical Hebrew originals, they're trying to argue for something that they can't get the text we have to support.
For me, it's a marker (like unto the usual rants about Constantine and the Nicene Council) that indicates I should keep an eye out for "quirkiness".
The two books I’ve read on the possibility of Hebrew gospels are:
Eusebius in his time wrote that Matthew had or might have had a Hebrew original. That's it.
“Eusebius in his time wrote that Matthew had or might have had a Hebrew original. That’s it.”
Yeah, there is no solid irrefutable proof.