Start in local language, or English?

Hello Fellow Indie Hackers!

I've been following the Indie Hackers Podcast and the forums for a while now, but it's my very first post here, so firstly I'd like to say hello!

I'd love to get your views on the following: for my next project (SaaS), should I start in the local language (Polish) or in English?

I mean choosing the language for my marketing site, and also language of the app itself.

I would say that clients for whom I consulted so far, who used parts of what I will include in the final product, around 50% of conversations were in Polish and other 50% in English. To make things more complex, the clients with whom I converse in English, have yet another local language of their own ;-)

By going Polish-only I'll prohibit my international clients from giving it a go, so it's tempting for me to do everything (marketing site, and the app itself) in English exclusively. On the other hand, locally where I live and clients that I can meet face-to-face, speak Polish. I definitely don't have the resources to maintain multiple language versions right now.

I'd appreciate if you could share your experiences with this.

Kind regards
Tomasz