If I have one Presence in a land, and I play Entwined Power on another Spirit who has one Presence there, do we have a Sacred Site?

If I have one Presence in a land, and I play Entwined Power on another Spirit who has one Presence there, do we have a Sacred Site?

You may target Powers as if you had a Sacred Site there, and they may target Powers as if they had a Sacred Site there. But for all other purposes, no, because Entwined Power only lets you use each others' Presence for targeting Powers - not for anything else, including resolving Powers.
For instance, Gift of Living Energy (a Minor Power) wouldn't count it towards "If you have at least 2 Sacred Sites...", nor would Fear of the Unseen (a Fear Card) treat it as a Sacred Site for scaring away Invaders.
Note that if you Entwine with River Surges in Sunlight, their River's Domain Special Rule only applies to them (read it as "counts as your Sacred Site"). So for targeting, they would treat any Wetland where either of you have Presence as a Sacred Site, but you would still need 2+ Presence as usual.