You should publish your materials (app, marketing, blog, website, etc) in the language that your users are comfortable in. If that is English, then it needs to

You should publish your materials (app, marketing, blog, website, etc) in the language that your users are comfortable in. If that is English, then it needs to be in English. Sounds like you have an audience that is multi-lingual, but English is that main language. This can be a challenge, but one you need to face. Also, keep in mind, if your app is awesome, users will forgive a few grammatical errors. Even native speakers make mistakes writing so a few errors in not a huge deal, imo, especially on a blog). Good luck!