An extensive in-depth review of Questra by the serious Belgian magazine Finance Lab, their outgo is simple: Questra is a scam, Alex Prochukhan and Cheslave Pestyuk are mentioned amonst the owners.

Read the full story here, Google translate helps a lot:
https://financelab.blog/2018/04/23/vermeend-ponzinetwerk-questra-kondigt-doorstart-in-belgie-aan/

https://s25.postimg.cc/hg6117gn3/prochukhan_belg.jpg