You make a good point. I am not sure who would, or even could do it. Over the years I have seen many collections of works, but none that actually have a complete set of Tárrega works that include all of the pieces that modern publications attribute towards Tárrega having actually personally composed.
There might be many reasons for this. One might be, for example, any case where Tárrega is known to perform a piece, but it is not known if he was the original composer. He may be credited in a modern publication by having his name at the top of the score, which is not entirely misleading since the music may have been by played Tárrega.
Like Sor/Coste for example, I suspect there are cases where students authored or at least revised some of the studies, technically making them the compiler or arranger, or perhaps even the original author of a Tárrega style composition.
If we look at TI ii-26 as a simple example, I have at least 3 different publications with this as Study in C major, but no Tárrega collection books I have contain this Study.
I would be curious if this book has it or uses the RCM numbering.
https://www.stringsbymail.com/karl-sche ... -6379.html
If my research doesn't produce an answer regarding TI iii- / TI ii- / TI i- numbering, I will likely buy a copy and continue on from there.
My only real fear of course is a purchase that leaves me with new questions and no new answers.