>>865,866
SE answer is slightly incomplete. Most archaisms in modern Japanese are read aloud as written and adjective conjugations fall under that, so that part is well and good because they were talking about a song.
But occasionally, words are written in historical spelling for the same effect but are read aloud with modern pronunciation because it's also historical pronunciation. E.g. 思ひ出 as omoide; from about mid-Heian this ひ represented a wi sound as a conjugation of ふ u verbs, and around Kamakura wi and i merged into i.
Unfortunately, it takes a little familiarity with old text to know which is right in any given case (but only a little, は/わ-row fuckery + the au → ou shift covers most of what I've seen). Fortunately, the exceptions are rarer in modern artistic expression than the "just read it as is" cases.