[pavlov]

I’ve been writing C and its progeny (C++, JavaScript, Rust etc.) since 1990 on a Finnish keyboard.

The AltGr brackets are fine. The truly annoying character to type is the backtick (which is a quite new addition to the pantheon of special characters, C doesn’t use it).

My personal opinion is that Niklaus Wirth had the better overall ideas about clarity and inclusiveness in programming language design, but that battle is long lost. (What you consider the character set needed for "proper programming" is really a relatively new development, mid-1990s and later.)

[schoen]

Backticks were fairly important for shell scripting in the past, but have officially been replaced with $(), which can be nested.

My intuition is that Perl would be the most challenging on a keyboard where it's harder to type unusual punctuation, since it feels like a very punctuation-heavy language, but I don't know whether it actually uses more than C (I think the backtick has a shell-style meaning in Perl too).