In order to quickly ramp up their navy the Chinese had to cut a lot of corners and using licensed European naval diesel engines was one of those corners.
The Project 20380 corvette is about as well armed as the average Western frigate. And the Project 22350 frigate is about as well armed as the average Western destroyer. And that is if you use the Uran missile for anti-shipping. If you use the Kalibr, Oniks, and Zircon, then they outclass any Western ship in anti-shipping capability. It is not like the Russians spent this time doing nothing. They had a lot of issues fixing the electronics in the frigates, and the corvettes had much the same issues when they changed the radar from the Furke to the Zaslon. The M90FR and M70FRU gas turbine engines had to be developed and put into production.
The Russians have 8 Project 20380/20385 corvettes in various stages of construction with 2 in trials. That is basically the same amount they have in service right now. And they have 5 Project 22350 frigates in construction with 1 in trials. Which is like triple the amount they have in service. Once the Amur shipyard finishes construction of the corvettes they will likely be switched to production of frigates. Severnaya Verf will likely start producing Project 22350M destroyers. In one decade they will likely have replaced all their high end ships with modern variants.
Western sanctions in 2014 delayed the modernization of the Russian surface navy fleet for like a decade. But right now all components have been replaced and ship production has resumed. There will be hiccups but not to the same degree as in the past.
Focusing even more on production of nuclear submarines would solve nothing. Sevmash production is maxed out. You could buy several frigates for the price of a single nuclear attack submarine, let alone corvettes.
A Project 22350 frigate costs over 18 billion rubles, and a Project 885M attack submarine costs over 47 billion rubles. A Project 20380 corvette costs over 10 billion rubles.
The nuclear submarines cannot do escort of merchant ships like the surface ships can do. Russia will need its own merchant marine and navy to escort it so they can do trade with India, Southeast Asia, Africa, and Latin America. The only reasonable way to increase production of nuclear attack submarines would be to stop production of all Borei and derivatives to focus on attack submarines. Both the SSBNs and the Poseidon carriers. What will happen is that quite likely once the current order for Borei Bulava and Poseidon carriers is finished, they will focus on the Laika attack submarine like I said.