The background to my question about comment replies has several parts, but I essentially have a single question.
When using StackExchange on my mobile, it does not provide me with autocomplete when I type @ followed by the first couple of characters of a name.
I now know that I only need to type the first three characters of a name—or less if it has fewer letters before a space and it is unique.
Recently, I was on a train and I wanted to reply to a comment left by somebody. However, that person's name was expressed in Asian symbols that I couldn't type on my phone. (At least not easily.) I could have copied and pasted all of the symbols (which were also separated by spaces), but I would not have had autocomplete to "confirm" it was correct—and I wasn't sure if it would be.
So, my question is, how do you know for sure if a short @name is going to be correct or not in the absence of autocomplete and in situations such as this where the name isn't understandable to you? Do you just copy and paste the whole thing, remove any spaces, and assume it will work?