I'm using 2 extensions from the Firefox store, Simple Translate and Translate This Page. If one goes down, I use the other. Sometimes I use translate.yandex.ru as well.
The last laptop I bought is a Dell Inspiron from 2013. I got it at a ReStore (Habitat for Humanity) thrift shop for $125 ~2 yrs ago. i5 processor; built like a tank. Had to replace wifi chip b/c original was very slow. Got that on ebay for $25 (pkg of 5, but that's the only way they came). When W10 goes away, I'll make it a chromebook, if I haven't first figured out how to install Linux on it. If I need a usb c port, I'll find an adapter, as that would put less strain on my budget.
I just looked up user agent. If I understand correctly, that changes every time I change browsers. Does it also change every time I clear the cache?