I heard back from my dealer. First of all, the receiver is made to operate in several different cameras, so to work in the Panasonic slot it needs a specific adapter plate, which comes with the one I bought. The 5p variant receiver (which is $125 more) doesn’t come with the adapter, so it is also $125 extra. The TA5 to dual Male XLR cable from Lectrosonics is $75. If I order now I can expect it to ship in mid September.
So I can pay $325 on top of what I’ve already paid to have it in September, or pay nothing extra and hope Panasonic delivers on the firmware upgrade 3 months later.
I’ve decided to wait.