Happy to help! ^^ Ofc, anyone can (and should!) use the time that makes sense for their headcanons, be it a tenday or a year, but I still thought I'd share in case it helps anyone still undecided.

(Epilogue spoilers) - If Karlach doesn't survive, Withers has a quote of, "in a dozen tendays, an entire life was lived".
I take that as the length of time the adventure took, as she fully lived while with the party.
(120 days = 4 months)
That also works for the seasons, start of game vs epilogue.

Idk anything about this book, I'm just disappointed whoever translated it to Danish went "creative" rather than sticking to translating the title like everyone else. (Rødt hjerte, blåt blod = Red heart, blue blood).

Put a Darkness spell or Darkness arrow around the portal. Helps massively to prevent ranged attacks on it.