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How would I quantify how significant the interaction is?

Determining the interaction energy between two defined monomers such as your aromatic Triazole and amide is a rather straightforward process. This process is referred to as the supramolecular approach. I'll point you to a paper that analyzes the benzene dimer. This method is strictly a computational one so a bit of knowledge in computational chemistry is necessary.

The Supramolecular Approach

The What

The supramolecular approach boils down to this.

$E_{int} = E_{dimer} - (E_{mon1} + E_{mon2})$

Here we have some interaction energy ($E_{int}$) determined from the difference of a dimer energy ($E_{dimer}$) and the sum of the two monomers ($E_{monomer}$). If both monomers were equivalent (say, you were interested in the interaction energy of the benzene dimer where each monomer was a benzene ring), you could simplify the summation to two times the energy of one monomer ($2E_{mon}$). In your particular case, you have two different monomers.

The whole idea is if I have two interacting molecules, I can determine the energy of each molecule individually (as if they were separated at infinite distance) as well as their complex. So as you bring these molecules closer and closer together, the energy starts to go down (the interaction energy).

The How

NOTE: Your geometry is from a crystal structure. Do NOT modify this geometry. You will want to keep everything exactly as is. This means you don't want to optimize your system. You do not want to eyeball monomer placement. Take everything from your known structure and be careful not to change it otherwise it can ruin this process. EDIT: We are modifying the structure by truncating and capping but intermolecular parameters must stay the same for whatever it is you are trying to model.

1. Define your monomers. You will need to determine what part of your 'dimer' system is important for describing this weak interaction. I recommend keeping the aromatic ring and truncating the ring with something similar to what is being truncated. You could cap your monomer with a hydrogen or a methyl group for example.
2. Define your dimer. Your dimer is simply a combination of your two defined monomers.
3. Determine the method you want to implement. Post-Hartree Fock methods are essential for this. Note that if you use the widely-implemented MP2 method, your answer may be way off (can over-estimate pi-pi interactions by as much as 200%!). The CCSD(T) method is recommended.
4. Determine the energies of your monomers and dimer. You will want to run a single-point energy calculation on your monomers and your dimer.
5. Determine the interaction energy. Plug your energies into the equation given above and determine the interaction energy. Convert to whatever units you wish to use (I prefer kJ/mol but most people use kcal/mol so you may want to use that).

I hope this helps. Looks like an interesting project to say the least.