No.
Treason is a very specific thing in the US:
Treason against the United States, shall consist only in levying war against them, or in adhering to their enemies, giving them aid and comfort. No person shall be convicted of treason unless on the testimony of two witnesses to the same overt act, or on confession in open court.
We don’t actually have any “enemies” right now and even if we did, the UK isn’t one of them.
But it is criminal.
No. They’ve conspired with the UK. Not just against the candidate Trump, but conspired to unseat him since he became President. That makes it treason.