I am using 126.96.36.199 firmware.
The RAK5205 is registered in TheThingsNetwork
I have setup my TTN application to decode the payload as LPP payload.
All the data sent by the RAK5205 are correctly decoded by TTN application excepted the GPS data.
After looking at the data, the data frame is too long compared to what is specified by LPP format.
By looking at the source code, I can see that you have added the speed at the end of the frame but it is not inline with the LPP format thus TTN is not able to decode the payload.
Unfortunately, since you only provide the project for Keil and I do not have it, I cannot correct the issue.