So I've been using your secondary VPE IRQ patches successfully for a while - just manually punting vrx200_rx, ath9k and ath10k onto the second CPU.
Since your earlier patches have been forgotten in the mailing list and your revised (non-auto balancing) patches are now upstream (well done on that), have you considered raising a pull request on OpenWRT github for including these in kernel 4.19 on git?
Just been dealing with the packet steering script issue, which mostly affects VDSL2 users who should be getting above 100Mb/s. See PR2553 for fixing it to use all CPUs but also disable it by default (in preference to proper IRQ balancing).