As far as I have seen, the unability of TTX, to decompile the feature params block shall not be fixed. When TTX decompiles the GSUB table, the tag is there, but empty (no link to the name table). But meanwhile (?) the names for the stylistic set features can be customized. The tag links from a ss-feature to the name table. SS01–20 link to name IDs 256–275. Implementing this would be very useful, because it is comfortable, if you can directly see the meaning of a stylistic set feature by its name in the OT menu of Indesign.