Taipei is 6 hours ahead of Barcelona
Best overlap: 8:00 AM to 12:00 PM in Barcelona is 2:00 PM to 6:00 PM in Taipei.
For a call that suits both sides, look at 8:00 AM to 12:00 PM in Barcelona / 2:00 PM to 6:00 PM in Taipei. Taipei is 6 hours ahead of Barcelona, which gives you a solid 4-hour window. Book earlier in it and neither side is rushing. These times hold for most of the year, but Barcelona's daylight saving (which Taipei doesn't use) shifts them by an hour twice annually.