Interference from one foreign language in learning another

[Linguoboy]

I think the very broad use of à in French causes me to overuse ni in Japanese where I should use de.

The differences between French, Spanish, and Catalan in the usage of a/à vs en make this a real headache for me (only compounded, of course, that in Central Catalan a is /ə/ and en is /ən/ so the distinction is very hard to catch at times).

Preposition usage in general is a nightmare because it's so arbitrary. Even dialects of the same language don't agree, so mapping the usage to the usage in another language becomes an absolute shitshow.

[linguistcat]

I don't know much Russian OR Romanian, but I often forget <спасибо> when I'm trying to remember thank you in Russian and substitute <mulţumesc>. I actually learned Romanian first (what little I did learn), and it seems to only go Romanian for Russian, not the other way. Probably if I learned more of both, but separated in time and learning environment, I might separate them out a little or I might get cross over going both ways, who knows?