We have the sources for BenF’s firmware, just not the latest version. He has previously stated that he does not see any reason to open-source his software if nobody makes something out of it.
This is a good opportunity to make use of the available source code. It should not be too difficult to paste the 9341 display routines into the old firmware code. The work can easily be forward-ported if we ever get hold of newer firmware sources in the future, or be picked up by BenF if he is interested.
I’ll try to help out with code questions if someone gives this a stab. I have even bought a 9341 LCD module in the hope of testing out firmware code on a STM32 development board, but unfortunately the module has only SPI and not parallel interface so I can only verify higher level display code but not the exact driving code. Getting something on the DSO screen in the first place, by developing “in the dark”, is the greatest challenge.