It's not just Arabic and Japanese. My Swedish/Finnish MacBook keyboard doesn't have the | and ~ characters printed anywhere on the keyboard. To type them, you just have to remember where they are. That's ok for me as a programmer, but doesn't work for anyone closer to a general user, which Urbit seems to expect because these symbols are used extensively in the command line UI.
Realistically there's no reason the interface can't simply autoconvert some arbitrary unicode character into a |, and leave that as an extension for anyone to add to whatever arbitrary language
It matters for reading/writing code, having uniform syntax, but it hardly matters for a general user's usage (in fact, I'm just talking about an alias, and its not so troublesome).
And regardless, this special character issue likely exists for any character; I imagine few are consistent among all languages, appearing on all keyboards.
So its just a pick your poison and stick with it situation, and whaddyaknow, English is still the most common internet language, and perl/bash have already ensured that most programmers have had to deal with these characters for decades
