from personal experience (i have 2x BT HHKB, one of which is stock, other is lubed thinly, 1 USB HHKB stock 2 years of daily use), freshly lubed HHKB is horrible, maybe unless you use thin lube. The problem is that it changes the sound profile and this sound has the effect of making the HHKB feel mushy. It will improve if you wait it out, and wait for the lube to settle, or you can open it all up again after a few days of use to "try" to wipe off the lube from the sliders. After that, then the smoothness is there, without the farty/mushy sound.
OR
you can just keep using your stock HHKB, and wear the sliders out. you can still open and lube the stabilizers, but for the slider housings, just wear them out. my best sounding/feeling HHKB is my USB one, which I use almost everyday at the office.