It was the episode where Ed and Al go to a village supposedly tormented by a ghost, and then they meet the alchemist Majhal or whatever his name is...basically, the man lost the love of his life (I feel like she even fell off a cliff, been a long time since I've seen it though) and became obsessed with, you guessed it, bringing her back via alchemy...he essentially wound up creating lookalikes of her that weren't really alive, and doing what almost everyone in that series did to try and revive the dead...but it turns out that the old woman who frequently visited him was the lover he thought died. Turns out she just got amnesia for a few years and when she remembered she came back, but as an old hag who lost her beauty, Majhal refused to believe it was her. He died being unable to see the truth that was right under his nose all along. ...or something. I really should try to watch the episode before typing a theory like this, but whatever, it was something along those lines.
So, is it possible that Kumasawa was the original 'Beatrice'? Then for some reason Kinzo thought she died, and maybe fell in love with a daughter the two possibly conceived, feeling like she was the only thing remaining of his lost love...but Kumasawa was right under his nose and he just got blinded to it somehow? So when she became an old hag, his mind was still so full of her youthful beauty that he just couldn't see it ("without love, it cannot be seen"; Kinzo blinded by her beauty would be lust more than love)...so Kumasawa stays on as a faithful servant, even knowing that Kinzo refuses to acknowledge who she is.
Problems with this are that Chiyo Kumasawa is most certainly a Japanese name...so why 'Beatrice', unless that was just the name of their daughter (since we know Kinzo named all his other kids western names as well)? The portrait of Beatrice in the hall...in EP1, Battler says if not for the fact that she didn't look Japanese, she could have very well been their grandmother. Not that I'm saying Kumasawa = their grandmother (obviously her children would know better than to not recognize their own mother, no matter her age; Kinzo just can't because he's lost it), but that it could still be a stylistic, westernized interpretation of a Japanese woman. Another problem is that in EP4 I think the boat captain says Kumasawa also knew about Kuwadorian when he says 'some of the older servants too', so she was a servant back then too...then again, it was only about 20 years before the present, and the 80-year old Kumasawa would have still been a hag in Kinzo's eyes at 60.
I don't know, I feel like it's full of holes, but that I may be onto
something. At the very least we know Kumasawa knows some things, she's been around for a long time, and she seriously tried to solve the epitaph. Her and Kinzo don't appear to have any obvious connection to each other, but that's also just as far as we're shown...and
So...I dunno. I'm probably way off, but I'm just throwing it out there. Only time will tell.