Does a Sacred Servant - with the appropriate Charisma Score - get to cast 5th level spells?
If I combine literally the "Spells" section for a Sacred Servant
...she also gains one domain spell slot for each level of paladin spells she can cast.
with the usual restriction based on the relevant Score
To prepare or cast a spell, a paladin must have a Charisma score equal to at least 10 + the spell level.
I would deduce a Paladin with at least Charisma 15 can theoretically cast 5th level spells, but is restricted by a "truncated" Paladin Spell List. If we interpret the line from the Sacred Servant rules as the access to a new Spell List that goes up to Level 9 I would allow a Sacred Servant to cast also higher level Spells.
Am I too biased?