This is all very new. I have yet to see a report from anyone who has used it. I have a lot of questions. Is there a TH equivalent of the CPL file? Are there conventions for the center of a TH part (Kicad uses pin 1 of connectors, is that it?). A number of parts do not have an obvious center given in their datasheets - like USB connectors (even SMT ones).
When JLCPCB added the TH stuff, I asked about guidelines and they said they were working on them. Haven't seen anything yet.