So the end product for the android app was more or less compromised by me going all out on working on the big industry project.

I did however find some extra information on the bluetooth communication problem where sent data would get scrambled along the way. By using various other bluetooth modules and some extra HM_10 modules I had laying around I was able to single out the problem. When I sent over data using a very simple bluetooth serial console and an immediate byte printout on the Arduino's side I found that the problem is actually the receiver of the bluetooth module. I knew for certain that I was sending the correct data and I also knew that the code on both sides was flawless and working correctly. In other words this is a hardware problem that I need to work around using software.

I plan to do this by saving which button I have pressed and in what state I expect that button to be in within 100ms from sending the command. If the button has not changed in that time I will re-send the command.

Once I have that done this will be a finished product ready for use in our boat!