All input is appreciated. I’ll get lots of feedback and run lots of tests before I settle on something final. Just because I’m sold on something today doesn’t mean I’m beyond convincing. Noto has lots of advantages over Arial that I could still get even if I ditch SemiCondensed. I’d also suggest trying to look at the font not side-by-side with Arial, though – while it’s a great way to see all the differences, Arial is a pretty wide font, so it may make a narrow font seem even narrower in contrast. Instead of the little side-by-side images, click through to one of the larger images and let it be the only one you can see, wait a bit, then see if it still seems too condensed when it’s not right next to Arial.
EDIT: There are complicating factors with ditching SemiCondensed, though. I believe the standard-width Noto font has what I’d consider an inconsistency between the capital and lowercase letters – the capitals seem more condensed than the lowercase. It’s not a huge issue but I kinda don’t like it (I’ll also double-check, it may have been some other variant that had this issue, like just the Medium weight or some such thing). More definitely, regular Noto is sometimes even wider than Arial, especially once you start adding weight to it, and I’m fairly set in my opinion that Arial is too wide for the job. SemiCondensed doesn’t have either problem – everything is the same amount of condensed, and it’s narrower than Arial even at a higher weight. So if we’re staying with Noto at all, SemiCondensed has an inherent advantage there. Also the fact that the proportions are very similar to the burnt-in alien subtitles in Star Wars and Jedi gives it a certain stylistic/thematic advantage in my mind. So if I ditch SemiCondensed, it’ll probably be for a different font entirely, and that will take some doing.
Another option is to just stretch the fonts horizontally. However, that will have a distorting effect as at some point in the stretching, the vertical strokes will start to seem thicker than the horizontal strokes. I could also start with a wider font and condense it, which has the opposite problem (and possibly also the inconsistency problem). I don’t like to stretch fonts as a general rule, but small adjustments might be doable if there’s a worthwhile improvement – I actually already do this for very long subtitles lines that go outside the display’s title-safe area (which is an issue for a handful of Greek and Russian subs), but never condense more than around 5%.