Speak, rarely, but when thinking, yeah, exactly what you describe. Also, sometimes there's a concept that's just described better in one specific language.
For speaking I have more of a “switch” going on. Besides, I'm always mindful of people around me not speaking my other languages. On the other hand… when talking to someone who shares more languages, I feel we can achieve some nice compression by mixing and matching.
I'm currently doing a subset of that, by writing a smaller game around the most difficult and complex feature of the game I started writing last year. So yeah, clearly I think it's a good idea, go for it.
An alternative I did consider before is dialing up the concept of vertical slices. To use your example, you'd release just one game, but for V1 you'd focus on making sure trading is fun and technically solid enough to work as a game on its own, then for V2 you'd add colony management and mature it to the same level, etc. But that strategy would IMO make more sense for a small studio or a simpler game… for a solo 4X, separate games is probably better.
I also concur with @Jeffool@lemmy.world in that releasing anything is really good for various reasons. Self-esteem, motivation, branding, and getting experience in the release side of things (store pages, marketing, the works).
Finally, speaking of solo, here's another strong argument: if you don't want to do it solo, releasing anything is your way out of that. You release the first small game, start getting visibility and revenue, and then you can recruit someone else and start a small studio. Release the second one and you can grow the team. Rinse and repeat.
Whee! おかえり 💖