Eternal Decks · Board game rules
With the festival card revealed we can play in any row, even a different row than the one with the festival card. In that case we must respect the rules of that row right?
Quick answer
Yes — the Festival's "play one or two cards to any Field row" ability lets you target other rows, but each card must still follow that specific row's own placement rules (plus the Common Placement Rules).
Details
The FESTIVAL Field Card itself only follows CAMP-style placement rules (no additional restrictions) for its own row, but its special ability is what grants access to other rows: "While the Festival is active, the following ability is always available to all players: On your turn, you may play one or two cards to any Field row and/or the River." [p.31 — Stage B Ghost Town / Ghost Town Field Cards]
This ability only changes how many cards you may play and where you're allowed to direct them (any row, not just the Festival's row). It does not override the placement rules of the destination row. So if you use the Festival ability to play a card into, say, a MOUNTAIN or CAVE row, that card must still satisfy the ascending/descending rule (or whatever rule applies to that row), as well as the Common Placement Rules (no same color or same number adjacent) [p.10 — Taking A Turn].
Watch out: If you play two cards in the same turn using the Festival ability and this triggers a Bonus or Revives an Eternal, resolve that only after both cards have been played, not after the first [p.31 — Ghost Town Field Cards].