To be fair, for a coin that will never be worth more than 1p, might as well clean it if you want. Doesn’t matter either way
No need for tiny people to engrave the small letters, normal sized people are fine. As for your your suggestion that there are no T's in the word Britain, have YOU tried saying it whilst omitting said letter ? The best way to explain how it is pronounced is the word BITTEN, just put an R in front of the B. As you can see, the T is an important letter.