Replacing the key cap [as a means of switching from QWERTZ to QWERTY] isn't going to help at all, it's just a label. You'd have to swap out internal parts too. Depending on the model, you'd either have to remove and swap typebars or remove the head off the typebar and resolder it onto the appropriate alternate (and ensure that it's properly aligned, not an easy task). Then you'd have to swap the key caps (labels). It's definitely a mechanically doable process, but it's probably almost never done in practice. Doing it as a newbie probably isn't recommendable; you're better off having a repair shop do it for you if you decide to go this route. Depending on the keyboard/model, you'd also have to deal with accents, umlauts, etc.

Given the difficulty (or cost) of the process and the potential end results, you're assuredly better off locating a QWERTY machine and paying a bit more for shipping to your area if necessary.

Your mileage may vary depending on model.

reply to u/imprisoningmymemory at https://www.reddit.com/r/typewriters/comments/1cg1avp/replacing_keys/

Typewriter Typefaces: Pica vs Elite, an explainer https://www.youtube.com/watch?v=qwCD69jUPps

Pica machines (12 characters per inch) will usually have a scale up to about 80-84.

Elite machines (10 characters per inch) will have a scale up to 100.

On Olympia machines, script only comes in Elite sizes (scale to 100 on platen).

https://amsterdamassassin.wordpress.com/2018/12/16/typecast-my-royal-fp-steampunk/