> perhaps due to indentation of Hacker News, so I manually applied since it did seem pretty straightforward
Yes, that would be exactly why. You can use e.g. `sed` to remove leading whitespace from each line (I used it to add the leading whitespace for posting).
> ... that said, it does do one odd thing (following is output on launching):
Yes, that's the warning I mentioned. The original code requests to use a buffer size of 1, which is no longer supported (it now means to use line buffering).
> It is much slower to render.
Avoiding line buffering (by requiring a buffer size of 2 or more) might fix that. Actually, it might be a good idea to use a significantly larger buffer, so that e.g. an entire ANSI colour code can be read all at once.
The other issues are, I'm pretty sure, because of other things that changed in how `subprocess` works. Fixing things at this level would indeed require quite a bit more hacking around with the low-level terminal APIs.
> I mean, I only formed my opinion that maybe there was a problem with python3 byte/string handling to just how many attempts there were... Were they trying to do things in a more idiomatic python3 fashion? Did the python3 APIs change? Does the error hint at something more concerning?
Most likely, other attempts either a) didn't understand what the original code was doing in precise enough detail, or b) didn't know how to send binary data to standard output properly (Python 3 defaults to opening standard output as a text stream).
All of that said: I think that nowadays you should just be able to get a build of NetHack that just outputs UTF-8 characters directly; failing that, you can use the `locale` command to tell your terminal to expect cp437 data.