Hi,
Once fop2 originates a call, control is then done by asterisk. If dtmf does not work is not something we can fix, not sure why dtmf will cease to work when originating calls from AMI.. it does not happen to me at least. It could be a bug in asterisk itself(?).
Regarding the language, it is also something kind of problematic. I know it is not a solution, but it is what I did myself in the past: replacing english sound files with my language files, as in many ocations I had prompts being play in english: sometimes in comedian mail, or other applications.
Call is originated, and if the channel driver is sip, the language set in sip.conf should be honored, but it seem it is not. There is a way to pass channel variables on originate commands in ami, but fop2 does not set any right now.