It is a massive penalty. It can be overcome especially if her willpower is lower and you have 0 wives.
View attachment 4338962
To bulldoze through the paragon penalty, 0 Willpower is a useful tool. I used NPC Debug to get my Paragon Milou to 0 Willpower and she will accept anything (I have 5 wives, the set limit for Aesir before penalties):
View attachment 4338999
Your Aria is a slave. She will agree.
And Buddhist conflicts with Aesir but it requires Aria's Buddhist Devotion to be higher than 60. I ran into this problem marrying Tori who is Cult of the Elder 95 devotion but did not ran into it marrying a Cult of the Elder Laika at 54 Devotion. Same stats so I checked the code and yep, Aesir conflicts with everyone not Aesir or Atheists but it requires a Devotion level of 60 or higher.
View attachment 4338980
This is a higher than 60 Devotion Buddhist Aria:
View attachment 4338982
View attachment 4338967