Seems to me that the Pronto, like many remotes, just doesn't have enough repeats by default for IR it transmits. it doesn't mean there's anything wrong with the Hex you see in PEdit (or posted above).
For instance, if you look at a Sony code in Pronto hex you won't see repeats. However, when a device receives a Sony IR code, it does expect to see it multiple times in a row. I've seen some people post 2 and others post 3. Sony's flagship Navitus for instance gets this right on single-key presses, but fails to adhere to the repeat count in macros.
For the Pronto, sure adjusting duration can fix such a problem, but it shouldn't be necessary. The thing should have a repeat count property and apparently doesn't seem to. Remotes such as those from RTI and Harmony support a repeat property and even allow it to be changed by the customer/programmer per device (RTI actually allows it to change per command).
Changing the JVC IRP to produce anything other than what's outlined in the various JVC documents would not be in the best interest of the community at large - regardless of what this specific Pronto remote does. Unless a special "Pronto3xJVC.irp" or something similar were made for this specific purpose.
