The ICE shouldn't come on at all until the driver specifically asks for HV mode or the battery is depleted.

Actually the OP never said that the Clarity PHEV was an experimental car, someone else said that.

Also you seem to be making some assumptions about why the OP got the car, which they specifically said they were not going to mention because that wasn't the point of their post. People buy cars for a variety of reasons. When I bought my first Prius in 2002 when hybrids were very rare, people kept telling me that I made a mistake because it won't save money. I told them that wasn't why I bought it. I knew the gas savings would not fully offset the higher cost, and I didn't buy it to save the planet, I was just fascinated by the technology and found it a very interesting car to own. The OP just said whatever someone's reasons for being interested in getting one, here are some things you should know which Honda won't tell you ahead of time, and it's also information that is not readily available online. That's why I really appreciated their post because I have come across very few first hand accounts by someone who has actually owned one. And none of those accounts went into this much detail about what it is really like owning one.

The OP clearly has no intention of getting another FCEV so no need to convince them. And I don't see the point in beating it into them that it was not the best choice, as they already said that. It was clearly stated that the purpose of the post was to provide information about lessons learned the hard way in the hope of helping others who might be making the same decision.

The entire Clarity line is experimental. This is based on Honda's historical usage of this nameplate - the current Clarities aren't the first time Honda has used this nameplate for extended on-road data collection.

Of the three current Clarity models, the PHEV is probably the most finished and capable but the reality is that it's way behind the Volt in driving dynamics. While the Clarity PHEV can drive anywhere in the country, unlike the FCEV and BEV variants, Honda reduced the PHEV's overall driving experience by using an electric motor that is too small for the vehicle. Both the Clarity Electric and FCEV have electric motors that can handle the vehicle under all conditions. The Clarity PHEV is at it's heart, a classic hybrid that gives priority to the electric drivetrain. The Volt was a BEV that used the ICE to extend the range. There's a fundamental difference in how these two approaches feel to the driver. Under heavy loads such as passing and short interstate on-ramps a classic hybrid will pull power from both the ICEV and EV power plants, resulting in slower and inconsistent response times to the throttle. The Volt always responds with the EV power plant, resulting in consistent response to the throttle. The Volt then uses the ICE refill the battery buffers.

Please note - I regularly drive both a 2017 Volt and a 2018 Clarity so I've experienced the above. The Clarity is definitely a more comfortable car to ride in, but the Volt is the better car from the driver's perspective, especially in high speed traffic.