TPE-PHX is nonstop because no one wants to clear immigration at LAX…
PHX-LAX-TPE on the return has no issue with immigration and allows pax to book with extended layover to visit friends and family.
You can see why CI wants to do this in the short term… they don’t have enough planes to launch PHX and still keep LAX 2nd daily and they don’t want JX to run away with all the PHX business.