On Sunday, Christopher Kula tested the mettle of his Pacific Collegium, artists-in-residence at St. Paul's Episcopal Church in Oakland, with a challenging set of Bach Cantatas (nos. 22, 182, 54, 49, and 106). Kula's programs are ambitious and often overachieving, but he was able to contract a roster of first-rate players on period instruments who normally sit in the front chairs of the Bay Area's best and more established groups. It was satisfying to see the Pacific Collegium come so far.