right, for all of you japanese speakers
nihongogo ojozu desu ne?
ee sonna
does that sound smart/rude/funny/etc?
“mada mada desu” should be the best reply to this phrase.
I don’t understand “ee sonnna” in this situation.
Gannbatte kudasai.
We say “iie sonna”, not “ee sonna”.
“iie sonna” is the shorter version of “iia sonna ni jozu dewa arimasen”. We often answer humbly.
As cherry said
you can answer " iie sonna, mada mada desu." It means that “No, my Japanese speaking is not enough.”
hi! yes I meant “iie sonna” - sorry for the confusion. I heard that the japanese, being the clever people that they are, like to shorten phrases so when given any compliment sometimes stead of saying the entire “iie sonna koto wa nai desu” they just say “iie sonna” - can I do the same when someone compliments me on my japanese?
Yes, you can say “iie sonna…” then smile shyly. You would sound and look very Japanese 
thanks!!!