The problem is that, when you execute a command like: SET MIDI_INPUT_PORT_PARAMETER 0 0 ALSA_SEQ_BINDINGS='0:0','0:1','14:0' the parser removes the apostrophes and calls SetMidiInputPortParameter with ParamVal="0:0,0:1,14:0", thus __parse_strings recognize it as a list with a single value: 0:0,0:1,14:0 instead of list with 3 values, and connection is made only to 0:0. And this affects all string list parameters.
I just commited a quick hack to lscp.y to fix this bug. As this device parameters job is a bit cumbersome, please check if all device parameters work now as expected and that this fix did not break anything else! Btw, I also commited a small refactoring of your introduced DB path arguments in lscp, you might remember that we discussed this once in an email. It's just a renaming of those grammer rules, so it shouldn't change any behavior, but just to let you know.