If you run those in cable tray without any shielding, you are asking for trouble. You are going to create a very powerful local FM radio transmitter. Think about what FM radio ntands for; Frequency Modulation, exactly what a VFD does.
Parallel runs is fine, if inside of grounded steel conduit. In open cable tray or PVC conduit , all VFD output conductors must be shielded. Aside from the RF radiation, cross induction from the different frequencies alone will give you no end of problems. Remember, when we run conductors next to each other in tray, they are all at the same frequencies, so any urial induction gets cancelled out. If the conductors are carrying different frequencies, as they would with VFD outputs, they do not. This makes reflected wave spikes extremely more likely and dangerous, often exceeding the insulation resistance of "inverter duty" motors. I recently witnessed a 250HP Baldor inverter duty motor get killed by this exact thing, and Baldor motors are not crap, their insulation is rated 2200V.