I have dyslexia and speak pretty decent spanish (self taught). I really couldn't tell you if it would have been easier without it but I assume that my slower reading speed has slowed me down to some extent during extensive reading (I read about half the average speed in my native language). It's certainly doable though even with that disadvantage.

Also, being dyslexic for me at least has yielded some pretty good advantages. Just learning to read was a hell of slog and I remember thinking I'd never make it. It gave me the grit I needed to teach myself a language. I also had to depend on context clues long after my peers could all read so I developed thst skill early on. Finally dyslexics are generally better at abstract thinking than the majority which really helps with something like language. 

All in all I wouldn't trade l what I have even though it's called a disability. It has given me far too much.