Don’t think I’ve ever had to delete terrorism-related spam, and I don’t have a ready answer. In the current form, I would imagine it unlikely that such content would be let through.
As for “one language”, one good reason for having a clear understanding of what’s being posted, is that forum posts are content published on RPS, as stated in the rules. IME, machine translation is simply too rough to make heads or tails of anything more than the very basic meaning, so if someone, for instance, used racial slurs, those would probably be lost completely in translation.
There are other communities which allow for regional spaces, OTOH, I wonder how useful that would be here, as the vast majority of non-native speakers have a language proficiency level that makes that unnecessary; off the top of my mind, out of the last 6 mods we’ve had, only one of them was not EASL.
On the plus side, you get people from different corners of the world talking to each other, sharing and comparing experiences*, rather than be segregated, which is the more likely outcome when users, who find it hard to express themselves easily enough, are given a dedicated space.
To offer a counter, this operates a selection: those who may have good reading comprehension, but not feel confident about their expressive skills, are less likely to get involved; think e.g. of the What Are You…? threads, most posters that do not meet a minimum requirement are automatically assumed to be spammers.
In that light, national or regional spaces could be fun, and even useful for native English speakers as a way to familiarize or practice a second language. At the same time, that would create a need for bilingual mods to take care of them.
- “What Have You Cooked” contained a sub-discussion about the different ways people cook in different places. IIRC some found the idea that gas cooktops are a thing, in some areas of the world, almost unthinkable, dangerous to borderline crazy.