If I play 2 Phase Shifts in the same turn, can I play two non-Logos cards? If I play Wild Wormhole, resulting in playing a non-Logos card, can I still use Phase Shift to play another non-Logos card?
It doesn't limit, it only enables. For every Phase Shift you play, you're going to be able to play one non-Logos card that turn. Here are some additional quotes from emails sent by Brad Andres (developer at FFG):
The Wild Wormhole is creating it own play permission for the card it is playing from the top of the deck separate from the play permission that the Phase shift is creating. Meaning that you can still play a non-Logos card from playing the phase shift.
FFG also addressed this in this video.