The recent (April 2018) extensive investigation how Questra works from the serious Dutch financelab.blog - it says Questra is definitely a harmful Ponzi-scheme:   

"The roots of Questra and AGAM are in Kazakhstan and Ukraine. Konstantin Mamchur, Aleksandr Prochukhan, Cheslav Pestyuk, and the Kazakhs Stanislav Kravtsov and Fanis Dzhuraev have been involved in all kinds of scams for years. They use the so-called MLM model (multi-level network marketing) that we see today at Questra (now Lianora), where members can build their own network and take off in a pyramid structure. If you are higher up in the pyramid by recruiting more employees, you increase your income because you earn a share of the commissions that your employees earn", - says the article.

https://financelab.blog/2018/04/23/vermeend-ponzinetwerk-questra-kondigt-doorstart-in-belgie-aan/

It's all in Dutch, but Google helps!