I think Robert and Bob are better examples. Native English speakers of all ages today are going to know that they're the same person, but someone in Russia might have trouble with those names if they were to read a Russian translation of an English novel.

(My first grade teacher in the 80s was named Margaret, but went by Peg with her students' parents, so I know this one. I wouldn't fault most native English speakers under the age of 35 or so if they didn't know it.)

More like “Richard” and “Dick.” You have to be explicitly told that Dick is a nickname for Richard at some point in your life or you’d likely never figure it out.

I mean, yeah, if I wasn't a native speaker I'd find those confusing, especially Margaret and Peg