The funny thing is the biggest beneficiary of the J-10C's debut will be the J-35. The list of J-10C customers is relatively small and shrinking, while the market for a 75M USD 5th-gen with permissive end user licensing is very, very large. Chinese military tech is also now seen as "credible" across the board. And since the J-35 will come with the PL-15 as well, the value proposition of a J-35 will be much greater than that of the J-10C.
I told a Chinese equity analyst to buy more Shenyang and short Chengdu, FYI...
Here is the problem with your argument. The reason China's arms don't sell is because of politics, not because other countries think China's arms are not good.
Buying Fighter jets are a huge political statement. If we look at countries with decent GDP and military budget, then who will actually be willing to buy fighter jets from China?
Gulf Arabs? No way US will tolerate it, and gulf are too much dependent on west politically to get into China camp that much.
Iran? China won't sell to appease gulf Arabs.
Latin America? Again can't afford to offend US and lacks sufficient military budget to operate 5th gen.
Europe is out, India out, Russia also out. West pacific US vassals also out.
Asean? Thailand and singapore are still too much in US camp to offend them by buying fighter jets from China.
Vietnam and Philippines hates China and still too low budget.
Indonesia again too low budget and would rather buy western to improve relationship.
So the only left are pakistan, bangladesh and poor African countries.
Egypt also too dependent on US. Algeria may not have enough budget.
Once you actually look at it strategically, J35 will have very hard time selling much. US vasaals are still too rich, and the global south still too poor.
J-10 has more chances selling to very poor countries looking to upgrade.
So no, don't short chengdu yet.