It's for this reason that when I receive a submission from someone whose first language may not be English, I might not always make corrections to change the poems to perfect English. While I still like to make corrections such as changing 'their' to 'there', for example, to make sure the poem is understood, I prefer to leave other things as they are - such as sentence structure. Sometimes in poems written by those with English as a second language, words might not be ordered in conventional English - but sometimes native English speakers change the order of words, or even make up new words, in their poetry. I wouldn't like to say that it's okay for native English speakers to not use conventional grammar, but to then correct non-English speakers when they do the same, whether accidentally or on purpose. That seems unfair. I prefer poems to be as unedited as possible so that they are true to the original voice of the poet. Plus, I think it's awesome when people can speak more than one language, and I am a little envious of anyone who can write poetry in a language that isn't their mother tongue!
And poetry is funny one for spelling and grammar, anyway. In fact, all creative writing can be subjected to unconventional spelling, grammar, structure and so on - depending on the intended audience. Sometimes I think it's best to put the proofreader in me to one side, and let the editor do her job, with a little less of the red pen and little more instinct and love of the creative.