I'd really wouldn't take it as an insult if a developer genuinely interested in helping me using the tool he made told me :

Excuse me, but I did not understand. Can you write in differently, or use Google Translate  ?

It is not rude, it simply means you're willing to help but have troubles figuring out their problem. Google Translate also has a very huge english corpus, so it usually translates well enough for you to understand the general meaning of its translation, which will help in extreme cases.

EDIT  : didn't see someone already talked about Google. Credits to him/her.

I'd really wouldn't take it as an insult if a developer genuinely interested in helping me using the tool he made told me :

Excuse me, but I did not understand. Can you write in differently, or use Google Translate?

It is not rude, it simply means you're willing to help but have troubles figuring out their problem. Google Translate also has a huge English corpus, so it usually translates well enough for you to understand the general meaning of its translation, which will help in extreme cases.

EDIT: didn't see someone already talked about Google. Credits to him/her.