Along with Tanaka, Yamada (山田) is also often used as a placeholder surname. It’s a comparably common name that’s also simple to read and write.
As for female placeholder given names, IMO the closest equivalent to Taro would probably be Hanako (花子). I’ve seen adverts that show sample credit cards or forms bearing these names.
For example, an ad for a Toyota financing promotion might feature the name Toyota Taro on the sample application form. Or in a Mitsubishi UFJ credit card ad, the happy-looking lady in the ad will be using a credit card that bears the name Mitsubishi Hanako.
That’s my usual approach for Bethesda games. After about six months, the community will have made some much-needed quality of life mods, and Bethesda will peobably have fixed any major performance issues or game-breaking, savefile-bricking bugs.
And this is supposed to be a huge game, so there will be a few serious issues as a matter of course.