It will apply to TIDAL tracks or local tracks. It’s actually a consideration of the size and complexity (and hence performance impact) of the Roon database that will result in holding information about 100,000 tracks. The Roon database is also the reason that Roon Labs say that Roon needs an SSD, rather than an HDD.
The source of the tracks (TIDAL, local, or a mixture) is irrelevant, AFAIK.