You did the right thing to remove the dead roots and potting into fresh bark.
The arial roots may be able to adapt to be under the media, but it is best to keep them on the dryer side while they adapt.
I have a phal which since last summer has just had two ex-arial roots under the medium and thats it. I'm not sure if I did the right thing but I acutally removed the plant from the medium twice a week for about three weeks, to allow the roots to fully dry, but kept it most most of the rest of the time. I did this to try and ensure the arial roots did not rot before they adapted.
It seemed to work, in that those two roots are still alive and now adapted to being in the medium, but the phal still only has the two roots many months later (but it's still alive, which is the good bit).
Many people on this forum advise KLN to promote root growth, but I've still been unable to get hold of it in the UK. There is a UK website called Orchid Accesories which lists it but their security certificate is out of date and I keep meaning to ring them but... well... I'm very very busy during work/office hours and get home every single day, see my 'chids and think "I've forgotten to ring again".
While it's difficult, I would personally remove the spikes with that little amount of roots left. I had to remove two on mine over the later summer months, because it seemed determined to spike rather than grow roots.