Roswell Crash was in July 1947, Transistor was invented 6 months later. You're saying they reverse engineered and reproduced ET tech in under 6 months without modern computers?
As an Electrical Engineer Anon, I find this unlikely.
Even if you consider the BJT the first "true" transistor, that was invented in Jun 1948, 11 months after the crash. It all seems rather unlikely.