It is not a concern for the Russians. If it were they would simply stop supplying the RD-93 and the JF-17 program shuts down as punishment. The JF-17 continues with a version of the same engine on frontline Russian (and Indian) fighters like the MiG-29K so it is obvious the Russians don't care. This is simple logic. You cannot "copy" a fighter, you need an industrial base to build all the thousands of parts. The J-11 is entirely made in China, including the WS-10 engine. The J-31 has no Russian equivalent and is probably more inspired by the F-35. China right now with its very many types is the only nonwhite nation that can build a 100% local aircraft that flies. The F-2 and T-50 use American parts and the LCA is mainly off-the-shelf European parts with an US engine.