This is to share my experience with other users who are considering installing this ROM. I had already written some of the problems last week, but I did not write about stability, because I thought I should spend more time to judge the stability.
In short, I think this ROM is stable enough to use as a main phone. I do not use a lot of apps or play games, so my usage may not cover a lot of things, but so far, I experienced only one system crash. It happened when I was trying to add a fingerprint. The UI became unresponsive, then the system UI crashed. Then the "Google" boot animation appeared and did not go away. I think probably the system itself did not crash, and under the animation the system could have been working, but since the animation did not go away, I had to restart the phone. But adding a fingerprint is not something a user would do a lot, just a few times when setting up a new system, so it is not a serious problem, I think.
Everything seems to work, including video decoding acceleration, so all apps worked fine, except, the camera app. Especially, the Google Camera app. It kept crashing and showed a message that was saying that the camera driver is crashed. When that happened, camera became unusable until a system reboot. So, I uninstalled the Google Camera app. But even with the default camera, if I enable HDR, it crashed while processing HDR. But again, I rarely use the camera, and I could just turn off HDR.
This ROM does not have scrolling lag that I had experienced with the Pixel Experience ROM, and animations and scrolling seem smooth. Overall, the performance is not worse than the official Lineage OS 8.1 ROM. Of course, it is not super fast/smooth or anything, but that is because the hardware is slow, not a problem of the ROM. Overall, I would recommand this to Nexus 6P users who want Android 10... except if you use camera a lot. I thank again the developer for this ROM.