I have updated the ZK Treasury according to the new API explained here by @kushti.
As kushti has explained, the previous implementation had some problems with complex statements which is resolved in the improved version.
Here is a joint spending created by ZK Treasury client apps:
https://explorer.ergoplatform.com/en/transactions/c3b9b47285c88ca709226e61f9f1dbf6a3c6e9261dafcd3ff82dd5faa740c913
Funds were protected by the following statement:
3-of-(A, B, C, D, E) && 1-of-(B, F)