The source of the documentation is here:
https://github.com/canonical-docs/snappy-docs/blob/master/build-snaps/your-first-snap.md
I’m not sure it’d be useful to add extra work-arounds to that snapcraft.yaml, since it would reduce its utility as a tutorial.
As for the bug you mentioned, the problem is almost certainly down to snapcraft building autotools projects with a prefix that differs to where the app is actually going to be installed.
Neither of the values for the install-via property are appropriate: one configures the project with a prefix of "", and the other with a temporary directory as the prefix. Neither option is appropriate for apps that compile in absolute paths based on the prefix (as is likely the case with GNU Hello’s bindtextdomain call).