Probably they worded it as “dedicated per-channel filter” meaning every channel has a filter control that can be used independently of the other filter.
Dedicated does not mean standalone.
Even if the controller has the ability to be used without the computer (mixing line/phono inputs) and then having hardware, standalone filters - as soon as you switch that channel to use software, all knobs become just a glorified keyboard buttons/knobs.
Exception are just two controllers if I am right - DDJ-SZ and MC6000mk1 (not sure about newer Pioneer RB controllers).
So hardware solution to OP problem is not possible but software one is pretty simple - change the Traktor map so filter knobs activate 92 filter from the FX section.