I see where you are coming from. Unfortunately I can't really comment on the claim via criminal injuries other than a general view in relation to the insurance claim but it may help unless a person with criminal law knowledge can qualify.
Anyway, my view would be that as you are making a valid claim against the negligent person's insurance then I doubt that the criminal injuries board would provide additional compensation. My understanding is that it is there to provide such compo where there is no other way of being reimbursed. Once they establish that you are claiming against the negligent person's motor insurance, I suspect they will close the claim.
If however the driver was uninsuredthere may be cause for claim however, where injury etc is caused as a result of a motor (RTA) incident then you would submit a claim to the MIB anyway.
I personally don't think therefore the CIB will entertain your claim. You will undoubtedly get a better payout from the insurers anyway. Also, depending upon what the guy was convicted of careless driving or dangerous driving will be a factor also.
Whilst I disagree, careless driving is viewed as a minor RTA offence which would not carry much weight, even dangerous driving these days you only get a slap on the wrist - unless you are eating a sandwich stationary at traffic lights

. Yes - I'm a cynic but don't start me about lenient sentences for serious legitimate driving offences i.e no licence/insurance/manslaughter etc.
Sorry, just thought I'd add the rant there.
Anyway, trust that all works out well.