I’m pretty new here and can say that, as someone who had done a bit of philosophy before at school before arriving, I was familiar with the definition of rationalism you link above but not with the rationalist community in the LessWrong sense.
Aware this is very anecdotal evidence, but thought it might be vaguely useful in some way.
I will, though, point out that you’re effectively conflating two different questions here: “What would it be easier for other people to call us, or how should we self-identify as members of a certain community in the public at large?” and “How should we self-refer within the community?” The answers to these questions do overlap, but the factors to consider when arriving at each answer are markedly different.
Yes you are technically correct, but in this case (as with most cases) I would like terminology to be universal. Eg I hate it that philosophy, economics and sociology sometimes discover the same things but then name them differently. I would like the term the ingroup uses to be the same as the outgroup uses. As Raemon said:
I didn’t think of ‘what others call us’ as the topic of this post, and think it’s much harder to change.