My take on this is .
The term propitiate had been used generally to include all kinds of unenlightened ' supernatural' beings like protectors, deities spirits , etc. One propitiates them in order to overcome obstacles or to gain some benefits ( usually for money and relationships )quickly to solve the problems we encounter in life.We will normally make a pledge to pay them back after we got our wish fulfilled, eg building a datuk gong , shrine or burning incense, making daily offerings or even animal sacrifices etc to appease them.
In the case of enlightened protectors, when the term propitiate is used, it should carry the same meaning as refuge.( also mean to seek protection ).
The payback after our prayers are answered are our virtuous actions from then onwards . We dont payback with ill gotten gains, material things, sacrifies or acts of harm as objects of appeasement .
Most importantly, there is no fear of punishment or retribution even if one does not respond with gratitude after a prayer had been answered.This is implied in the term propitiate. However if we pray to unenlightened beings, we can incur their wrath for failing to appease them. Besides there is always element of fear when propitiating them as we never sure they will demand more since they do not have great compassion which only enlightened beings possess.
Hope above helps.