Best approach for ASYN & SYNC Jobs

Question

Existing Scenario:-

Application need to design for 16+ countries and each country have their own independent site with same code base and functionality -> Only difference is data & configuration.

As depict in below diagram, Each country have their own jobs (i.e. Windows Application) with multiple tasks (i.e. Console Application), where windows application invoke the console application one by one and its execute in the server.

Technology &Database :- .Net (C#) & SQL Server

 

Note:- Some of the task does lots of processing, I run for 2-3 hours.

 

Please suggest or share your view -> What should be best approach to implement the same.