I have seen none of the stability issues that you’ve seen. My 4A is running as solid as ever.
I was able to install mraa and get my fan working again properly following the steps here: How can I use mraa? - ROCK 4 Series - Radxa Community
My display stopped working again, but I can live without that.
I agree with others who have commented that the software and documentation for these devices are woefully behind the times. To have distributions that are four years old and older as the newest “official” ones available is somewhat absurd.
Matt