After seeing a user report of trying to use JSON with tc, started to fix some of it.
Found a surprise. The display of U32 filters confuses IPv6 and IPv4. The code in tc/f_u32.c is obviously wront in print_ipv6(). It is just a copy/past of IPv4. Almost want to just remove the bad code and let it dump the raw filter. There is still lots of code missing JSON in the Tc filters. Volunteers and patches needed.