Really good effort, @gonsolo! I’ve been playing with Ardour+VPO myself for orchestral works (a couple of symphonic poems with a soundtrack feel), and while it’s been a challenge I too love how good the results can be.
I did start from a template, though, an excellent one made by Michael Willis:
Michael’s template has the advantage that panning and reverb (via the excellent Dragonfly Reverb) are already set properly for all the instruments, and is very easy to extend. Besides, it uses sfizz to load VPO, even though it uses the performance VPO files by default; since I needed a different approach, and the ability to change articulations dynamically via CC messages (that I could script) rather than keyswitches, I refactored some of the VPO SFZ files for the purpose:
The whole approach is described in detail in a couple of posts I wrote on LinuxMusicians, if you’re curious, specifically those related to the symphonic poems I worked on: