The effect they're talking about comes from the peppercorns, not the peppers. You heat them slightly in a pan and then grind them in a mortar and pestle. I run them through a fine strainer after that, but I dunno if you have to.

You should see if you can find some Japanese pepper. I find it has a stronger effect than the Szechuan ones. It's not like a numbing so much, but it makes your lips tingle without making your tongue burn.

Or maybe the problem is just needing the fresh varieties instead of dried. Even black pepper can be comparatively spicy when eaten fresh.

https://en.wikipedia.org/wiki/Zanthoxylum_piperitum