Yes, that channel can be trusted for accurate information. Composers are only credited for songs that they are explicitly confirmed to have composed. Since almost no Falcom albums provide composer credits by track, this might be through questioning on Twitter or information from an interview, or it might be thanks to composer codes that have been found in the files of a few games.
Also - while neither is explicitly confirmed, Mighty Obstacle and Innocent Primeval Breaker are virtually guaranteed to have been composed by Wataru Ishibashi and Masanori Osaki respectively. The
original version of Mighty Obstacle is wholly unlike anything Sonoda has ever done (and we know that Ishibashi did the majority of Ys VI's soundtrack), and the
pre-production version of Innocent Primeval Breaker uses Osaki's very distinctive synths.
(The guy running the channel is《J》here, by the way.)