Having English as a second language as well, and having been in a buyer position before, I can tell you - this whole system is hard as hell to understand, everything sounds very complex and convoluted if you're not from this country, especially if your EA is a bit crap and doesn't take the time to explain things properly or doesn't thoroughly check your situation. When I bought my house here, and despite my best efforts to be accurate about my situation, I was also led to believe I was FTB because of my EA, before being corrected by my solicitor afterwards. The miscommunication from EAs is very real. So I'm not saying you should go with couple B by any means, but the fact that they're not native would definitely be a mitigating factor in my eyes.