Decide your goal: match heat level first, then match fruity pepper flavor (roasted/sweet vs sharp).
Start with the listed ratio for your substitute, then taste your dish’s sauce/base for warmth after it heats through.
If the substitute tastes too sharp or flat, balance with a small pinch of salt and a drop of acid (lemon/vinegar) to mimic espelette’s roundness.
If it’s not hot enough, add heat in tiny pinches (especially for paprika-based swaps) and re-taste—avoid overshooting.
For finishing, use the substitute more lightly so it stays fragrant, and for sauces/braised dishes use it during simmering.