Intake manifold condensation causing cold start rattle / shudders

TLDR summary below.

Hi fellow Prius owners,

I have some issues with my Prius, and I'm having a hard time getting it resolved. It's a 3rd gen from 2009 (2010 model year), with about 230k km (143k mi).

First the symptoms. Since a few years I've had intermittent cold start rattles. It's usually only a few knocks that go away in less than a second. In a handful of cases the knocking has persisted for 5-10 seconds. In addition to this, the car occasionally shudders while accelerating in a turn, with the ICE at medium RPM. These shudders happen especially after a long highway drive. When I take the exit, come to a stop at the light and then turn left or right. The car shudders when I accelerate through the turn, which lasts a few seconds. I also get the feeling that in general, the engine is a bit rougher and louder than before, but maybe I'm just hyper alert to any unusual engine noises. I have not lost any coolant.

I've mentioned this at the dealer numerous times, but they just perform the Toyota prescribed maintenance and check for codes. They said the cooling system is not pressurized so there is no evidence of HG problems. They also denied that the Prius 3 is notorious for EGR and head gasket issues, which felt a bit like gaslighting to me as there is plenty of evidence to the contrary on the internet.

Two years ago, I completely cleaned my EGR system: EGR valve, pipe, cooler, intake manifold, throttle body & PCV valve. This seemed to resolve the issues for a few weeks before they returned. The car never had a check engine light or codes. I still suspected a HG leak so about a year ago I performed a block test (blue liquid) which turned out negative.

Since about 6 months the shudders have gotten a bit worse and they also happened during highway driving. I took it to a HG specialist, who exclusively fixes Toyota hybrid head gaskets. He checked the cylinders with a borescope, with a pressurized coolant system, and found no evidence for a leak. In fact, he said the engine looks to be in excellent condition. However, he did take off the intake manifold and there was a lot of water in the pipe leading up to the EGR ports, at least a few teaspoons full. He said this was probably condensation from the exhaust gases coming through the EGR system. The engine shudders during turns probably result from water sloshing around in the intake manifold due to centrifugal force, which causes it to block EGR ports or to enter the cylinders leading to misfires.

He cleaned and dried the intake manifold and sent me on my way. In the following weeks I had no cold start rattle or shudders, but then they returned, just as they did after my EGR cleaning.

I should mention that my highway driving is usually very calm, taking it easy behind some trucks in the slow lane . The HG mechanic thought that might have something to do with extra condensation buildup. He said he had never seen it that bad.

TLDR:
To summarize, it seems the cold start rattle and engine shudders are due to EGR condensation buildup in the intake manifold, leading to misfires. This seems like a plausible explanation. However, I still don't understand why this is getting worse over time. Is there anything I can do to prevent condensation buildup? Could the condensation perhaps point to an underlying problem with the engine?

Grateful for any ideas/suggestions.