Yes I know you are using some other libs too but the errors relate only to your code.
I posted a clear error for you earlier. which came from the real build output window and not the Errors List which is hard to read.
My recommendation is to close the Errors List and never open it again. With the output window you will have something that is close to what the arduino ide will produce.
As I have stated the error clearly shows that a #define from your project header file is not available in your library code.
You have said you can see your defines in your project but that is because you have header file that creates the defines in the project. The file is RemoteControllerDefinition.h
So the problem put simply is that #defines from project\RemoteControllerDefinition.h are unavailable in a library code BJBufferManager\BJBufferManager.h
That is correct. An Arduino library has no access to project code. It's a basic rule.
In the BJBufferManager.h you have commented a previous attempt to #include RemoteControllerDefinition.h. That attempt would have failed intellisense parsing and also the build would fail objecting to a missing RemoteControllerDefinition.h. Vs shows you it can find your #defines without need for #include because it assumes the code will build as one program but libs are separate.
Solution
You should un-comment the #include in BJBufferManager.h but change it to this:-
#include <RemoteControllerDefinition.h>
Then add a compiler include for the project folder as follows using "project property>extra flags". No need to hard code a path use the build {variable}:-
-I"{sketch_path}"