If they take low hours guys I expect it would be locals or African pilots? the problem is if you train expats then 500 hours on type later it's sayonara, I have something better elsewhere. On the other hand if you could go for it and they bonded you, do want to take a risk the size of your bond that they will be around long enough for you to get your hours on type? Just make sure it is structured correctly, in other words.
The visa thing I expect is harmless, UK and US are 2 destinations they fly to and they definitely did their training in the past in the UK, so they wouldn't want any grief getting you into a sim in LGW for example.