I put a URL from the community into the gogole rich results test. Here are the results:

I don't know what effect rich results testing has on SEO. Is this very important?
A link test on the Discourse forum:

A link test on the Flarum Forum:

Opera Mini: Categories take very long to load, clicking on a post turns the page blank most of the time.
LG webOS and Wii U browsers: Clicking on a category turns the page blank with only the top bar and loading indicator.
Nintendo 3DS/2DS browser: Works, but icons show up as boxes.
MyBB and PhpBB worked perfectly on all of them. It looks like NodeBB is just a little too complex for simpler browsers...
Opera Mini makes me really worried because a lot of people on poor data plans or phones use that.