In my opinion, there is no safe place, but I can prompt you to accomplish these achievements as quickly as possible :)
Below is my suggestion.
The best place to collect Broken Dreams
is near depot and temple. You can collect them while standing afk in protection zone.
Here :
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And one of the better places which is located at
here :
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Running to the NPC for the road you can find a lot of these glowing trees from which you can collect Broken Dreams.
Half-Buried Face
you will find in these places (marked on the map with a skull):
In the place marked with red circles there are a safe spot on the stairs.
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My way is that you run quickly to every face, use this energy bomb
or energy wall
in critical situations. By the face I stand on the energy bomb to be able to quickly recall the butterfly. In this way I achieved the achievement very quickly. Unfortunately, we can carry out missions every 2 hours so it is time consuming after all.