Thanks Bob that's a useful tip for anyone with similar problems. Although I'm not sure why you're seeing "coarse, crosse, krause" because FS2Crew tries to match what it hears with a list of commands it understands, which none of those words fall in to. It is picky however, you need to say the whole command otherwise it ignores what you said (e.g. you have to say "gear up" or "gear down", you can't just say "gear").

I can't say I've ever encountered FS2Crew reading back then not carrying out an action. However, some voice commands are you telling the FO what you're doing, rather than asking them to do something, so watch out for those. Whilst that wouldn't affect the flaps though, it would affect the autopilot; saying "nav" on its own means you're telling the FO you've pressed it, whilst saying "select nav" means you want the FO to press it. Sounds a bit nuts but it's for situational awareness, no one messes with the autopilot modes without telling the other pilot what they're up to.

In some aircraft (don't think the Q400 falls under this) some commands are you telling the First Officer what you're doing, rather than asking the FO to do something, so watch out for those. For example on the Jetstream 41 if you say "nav" that means you have pressed the nav button and are letting the FO know, if you want the FO to actually do it, you have to say "Select Nav".

After a summer break I'm back and would like to thank Bob for his great explanation on how to adjust the voice recognition. It would never recognise 'arm', so sorted this now.
Never had a problem with 'crosscheck' though.
Flew last night and asked FO to "start engine two" and it displayed the text correctly but got no response from FO. Tried again for engine one and same thing. Will have another look at this today. FO responded fine for rest of flight.
I really like FS2crew and the more you use it the more intuitive it becomes and I think it adds another level of realism that is worth the effort to set up and learning to use it