There are many non-English markets where the users have quite a high level of English, they just prefer using an app in their own language. This means that you could consider translating the app to these languages, while still having customer support only in English. For example, in the Scandinavian countries, most consumers (of apps anyway), would understand that an app does not have localized customer service.
Also, if you get customer support emails, you could hire someone to translate, just the text and your response. This will work in the beginning (although it is expensive), while you see whether these non-English markets have any potential at all. It is better to do it this way than investing in a setup, just to see that your app flops in these markets.
If you get any customers, that are really disappointed that they cannot call you and talk to a native speaker in their own language, then give them something for free. This will be way cheaper than setting up such customer service.