Denti,
Interesting observations to say the least, some of which have certainly prevented the widespread use of RNP AR, especially with ATC. Your comments relate to a common , albeit very common, misunderstanding of the coding of the procedure. (can you send me a PM on this issue)
Note: the SPD issue can be resolved in the coding of the procedure...
Currently, the GBAS system signal is capable of broadcasting curved paths, but is not certified to date.