I hope this helps.
I'm fluent in Dhivehi (native) and English. They are very different from each other. I've tried to learn Spanish few times. On and off, but I can't seem to really go anywhere (partly because I wasn't that interested and I didn't use proper techniques). Phonetically however, the 2 languages I speak together covers almost all the sounds used in the Spanish language. I've had more issues with remembering words rather than finding the sounds too different and hard. I also didn't like how Spanish uses the accented letters such as á è ō (because that's pretty much all I have to learn in relation to letters and sounds).
But it's been about a year and a half since I started learning Japanese and I find it quite easy. Maybe because Spanish is closer to English (my second language) and Japanese is closer to my first language? Idk. That's just my personal experience :))
Also take note that Dhivehi uses most of the sounds in all of these languages. For example, the English T is considered as the equivalent of Japanese and Spanish T. But they are pronounced differently (Spanish and Japanese T is soft). An English speaker would probably pronounce it like a normal English T. In dhivehi however, both of these sounds are 2 distinct letters. So I did not have to learn any new sound.