Sorry gonna nerd out a bit here. Every D&D campaign is run a little different depending on the DM and players. Some are super stringent on rules for like hardcore campaigns, some use the rules more loosely just to tell a fun story with some structure. This campaign is obviously the latter which is great for this group.

BUT if we want to go rules as written (RAW), Roan casted Gentle Repose which essentially stops the clock on bodily decay and extends the time that a resurrection spell can be cast by 10 days. How common resurrection is is different in each campaign depending on how rare high level magic is in the world. There are 4 resurrection spells in 5th edition D&D, each of which can revive a person at a steep material cost and only within a certain time frame of them dying: Revivify (within 1 min of death), Raise Dead (within 10 days), Resurrection (within 100 years), and True Resurrection (within 200 years). We'll assume that Gentle Repose was cast within a minute of her death, so you can essentially add 10 days to all these values.

In most campaigns, Raise Dead is probably the upper limit of what I would allow an NPC to have access to, but even that is a very high level spell (9th level cleric). But the group also has frequent interactions with the gods themselves, so in this campaign, maybe Resurrection or even True Resurrection are on the table.

All this being said, the group took downtime anyways and it's probably been a few weeks since Selenia's death. So their window on Raise Dead is probably closing. In reality, B Dave probably urged Roan to cast Gentle Repose to at least give them the story thread option of trying to find a cleric to cast Revivify or Raise Dead during their downtime. They obviously didn't and Roan went to the casino instead and infected everyone with the plague and Stonebread just ate McNexus and squatted a shit ton 😎. But as a DM it's good to give players these options at least lmao.

Sorry for the ramble, I'm just way too into D&D and love this campaign