Involved in the biosynthesis of rosmarinic acid, a compound with antiviral, antimicrobial and anti-inflammatory activities. Can use 4-coumaroyl- and caffeoyl-CoA as hydroxycinnamoyl donors and 4-Hydroxyphenyllactate and 3.4-Dihydroxyphenyllactate, but not shikimate or quinate, as hydroxycinnamoyl acceptors. Can also putatively catalyze amide formation with D-amino acids as acceptors. (2R)-3-(3,4-dihydroxyphenyl)lactate + (E)-caffeoyl-CoA = (R)-rosmarinate + CoA Optimum pH is 7.8. Belongs to the plant acyltransferase family.