There is, of course, no way to prove it was him, which someone always points out. And, of course, that's true. However, it is a logical conclusion. Tesla is known to have "revised" some of Edison's work in nearby Bellefonte and he was active in the Altoona area at the same time as my great-grandmother's journal was written. He is also known to have been in both Clearfield and Mahaffey. In order to reach either of those two places, he would have had to pass through my hometown as the Pennsylvania Railroad was the only passenger line that came up the Allegheny Front and across the Allegheny Plateau. PA's mountains are a complex system and, back then, challenging to navigate.
The man also had the skill to "fix" Edison's work, and I doubt there were many "odd Eastern Europeans" running around this area that could do such a thing.
My dad is an electrician by trade and did some of the work to update Beck House's wiring and he never saw anything like what he encountered when he first started working on the house. He called it "genius" and at some points, didn't want to touch it because he didn't understand it.
My mom's family were letter writers and kept journals. I have all of them, some of the first in Danish which I've had a professor at Penn State translate for me, in a safe deposit box. Much of what we know about local history comes from those letters and journals and a lot of it wasn't very pretty.
My dad's side of the family had more visual storytellers, including my grandfather who probably should have been an artist rather than a coal miner. Over the years, I've made it a point to collect what we have left from them of that nature and preserve and protect it.
... to tell more.
So awesome to know about your ancestors life!