If you just mean the part about advanced weapons from America then I agree with you, it's nonsense, obviously an accurate rifle can be manufactured anywhere.
The not an accident part has a decent argument. Considering that only a few shots were fired, one hit the dumpster she was hiding behind and one hit her in the head, it seems unlikely it was accidental.
Do you have a date or news article for the initial border attack by Israel in Metula? I thought that the initial attack was Hezbollah firing rockets on Oct 8th.