We must remember that Luke is NOT an eye-witness account and Matthew is very unlikely to be. And you've hit on one of the ares where there are reasons to doubt John.
We can tell that there are two rival traditions. In one the post-resurrection appearances took place in Galilee, while the other places them in Jerusalem. Matthew follows one line, Luke follows another and John appears to be trying to have it both ways.
It is implausible that the author Matthew would forget about the miracles of Pentecost or that the story would be lost to him. Likewise it is implausible that the author of Luke would be so against appearances in Galilee if he believed in those stories.
And if Christians were disputing over two incompatible stories at the time when Matthew and Luke were written how can we trust either story ?