Need to translate in-app texts in mobile app to Spanish via crowdin

I need someone to translate and proofread in-app texts of our mobile app via Crowdin platform from English to Spanish. Right now we already have some text translated, however, we need to proofread and correct it. Also, we are still missing some translations, thus we need to translate those. (approximately 10.000 words - 7000 proofreading and 3000 translating) For localisation, we are using Crowdin platform, thus I am looking for someone who is willing to use it as well. Translator/proofreader should know the app first - thus downloading the app first would be kind of necessary. I am looking for someone to cooperate with on a long-term basis, as we are having new strings of text approximately once a month.