I recently tried to compose a sentence to some who told me they were translating a book from English to Chinese. I responded to them:
As I am not a native speaker and my Chinese is quite poor, I cannot tell whether it will sound natural to a native Chinese speaker, or is just barely-passable 老外中文.
Notice that I have omitted the 因为 that should be there to match the 所以 clause. My understanding is that it is okay to omit either one or the other and still have the meaning understood, but I'm sure there are complex rules about which can be omitted in different contexts.
I also had originally started the second sentence as "不幸我的中文..." with the intended meaning of "Unfortunately, my Chinese...". However I chose instead to separate it into an introduction as I wasn't sure whether 不幸 prepended to the beginning of the sentence would make it harder for the absent 因为 to be inferred. I decided to try to play it safe and instead say "It is very unfortunate; my Chinese...".
After my first 我 I omitted the second one which could have gone in "所以不可能帮你们". My understanding is that in Chinese you do not repeat 我 as much as you do "I" in English. I did, however, use it for the next sentence which introduces a new topic.
Finally, the second sentence seemed a little convoluted to me and while I think it is understandable, I don't think it seems natural at all. My intended meaning was "My Chinese mastery is insufficient, ...", but again I think this part is clunky and unnatural.