It looks like you're new here. If you want to get involved, click one of these buttons!
Is there any documentation on how to implement a simple staircase for contrast threshold procedure using the builder?
There are old stair case plugins written for much overhauled versions of Opensesame. The code won't work anymore, but the logic applied there can be used to implement a staircase.
See here for example: https://github.com/smathot/OpenSesame/blob/3ca9cf4a4765fc12216f0a2a5ed191f74340474c/opensesame_plugins/quest_staircase_init/quest_staircase_init.py
Maybe older discussions on the forum will also be of use to you.