The paladin’s divine sense ability, and the detect good and evil spell, presuppose the existence of both consecrated and desecrated ground. The paladin ability further suggests one way to create them.
you also detect the presence of any place or object that has been consecrated or desecrated, as with the Hallow spell.
Note that by saying "as with" the Hallow spell, rather than "by" the Hallow spell, it is implied that there are other ways to consecrate or desecrate ground. This is further implied by the strict size and shape permitted by the hallow spell but with the DMG description of desecrated ground allowing it to be "of any size".
Both the spell and the ability reveal that objects rather than areas may be consecrated or desecrated as well, an effect that is not brought about by the Hallow spell.
Thus it is clearly established that while the Hallow spell is one way to produce consecrated or desecrated ground, it is not the only way.
The DMG describes the only effect of desecrated ground as
Undead standing on desecrated ground have advantage on all saving throws
which is noticeably weaker than the effects of Hallow.
I am currently running Curse of Strahd, and would like to have some of the churches be merely consecrated ground, and others be hallowed (which would be a stronger effect).
Since there does not appear to be a rules description of the effects of consecrated but not hallowed ground, for the purposes of my game I would like to treat consecrated ground as
Undead standing on consecrated ground have disadvantage on all saving throws
(to mirror that of desecrated ground in the DMG) and
Undead standing on consecrated ground take d6 radiant damage at the start of their turn
(to mirror the DMG description of holy water purifying desecrated ground, to provide a cinematic effect of Strahd zombies bursting into flame as they attack a church, and to provide PC’s a safer zone where they may be attacked by vampires and vampire spawn but at least their foes can’t regenerate)
To balance this second effect I would add the following to desecrated ground:
Celestials who use their Healing Touch while on desecrated ground have it count as two uses toward their daily limit.
Is there any description of the effects of consecrated ground already existing in the rules that I have missed?
Would providing these benefits to the consecrated ground at the various holy sites within Barovia disrupt any plot points or unbalance any encounters within Curse of Strahd?