This question is very easy to answer for me...
6 months ago I joined Steem, after a year down going back between my bed and the hospital. When I arrived on Steem, they were no french community. I decided to start it, to build it, without even looking at the english community.....
If i had the chance to change something, I would not play it like that.
I would first get to know the english community (but I was scare about my english), get friends, explain the need of a french community and start building it with support. And I would start to blog in english and ALWAYS duplicate in english my content !!! At least the statistics to show the change the french community was facing because of the growth !
Because now, even after 6 months on Steem, almost no one knows me in english community and I struggle to get attention and support for building a community (support for me +250 educationals videos / articles / website / French Minnows coaching).
This was the worst move I could do. Doing things, alone, by myself, in my steem corner.
But I did it... Now, I have to learn from this and try to correct it ! :-) 2018 look brighter already ! :)
You could easily do both! I hope you keep making English speaking friends while helping to develop a French community here!