This is probably more for CSL 1.2 than for CSL 1.1, but anyway: The way multiple publishers are dealt with is not ideal. SBL Handbook of Style, p. 83 requires this formatting Gottingen: Vandenhoeck & Ruprecht; Fribourg: Presses Universitaires, which is not possible with standard CSL. (CSL-M includes a “hack”, to quote @Frank_Bennett here.) Perhaps this requires a deeper change in the data model, like treating publisher and publisher-place as pairs, something like name parts.