Everyone throws around the concept that the reason why sales are low is because the domestic variant is of lower quality, but the problem is, there really isn't much documentation stating that. On paper, the quality of the Russian made goods is the same as any other brand, maybe with some few exceptions where avionics is indeed somewhat behind. But my major thinking on this is that they move to a mixture of domestic and foreign is to have sales overseas with countries that are interested in purchasing a cheaper aircraft but have at least the sources for spare parts closer to home. Problem with this thinking though, is what reality will show, that majority of sales are of domestic consumption in Russia, and not abroad, with maybe 50 or so jets abroad, while rest are at home. As an example, the SSJ-100, they had problems with foreign suppliers, just like what people love to say about Russian domestic. So if that is the case, then both are the same. How would brake systems or landing gear from lets saying domestic Russian source, be much different than counterpart? It appears that landing brakes and or braking systems on various other Russian jets seem to work, but somehow, it wouldn't for SSJ-100? I am not denying that maybe foreign one is good. But what about domestic?
There are lots of factors, but not much is said. So technically, everything is ending up with pure speculation and as soon as one mentions what could be an issue, everyone goes haywire about it. Some people are far too sensitive, and I am starting to think westerners are (especially when you question their industry).