One option is finding old switches of other types as spring donors. For instance, Alps, SMK switches, Omron B3G-S switches, KPT switches, other simplified Alps clones, etc. all have springs with approximately the same diameter, and various stiffnesses and lengths.
Another option is to get some very sturdy wire cutters, and try cutting a few loops off every spring.
I think what I'd like in the Click switches is a coil spring with a higher spring-rate, like MX-Clears, which ramps up the resistance faster per mm of compression.
What you want is a stiffer but shorter spring then. I recommend getting black Alps switches and snipping off some of the inactive coils. Iím not convinced thatís actually the feel youíre looking for (Alps and MX switches have fundamentally different force curves), but itís worth trying out.
So, unfortunately, there really isn't currently an option to go lighter with either of the quiet Matias switches. You CAN swap one of the quiet switch springs to the clicky switch to lighten it, though.
I recommend folks with Matias-switch keyboards get some linear switches and some clicky switches and swap the springs. Makes an improvement to both, though the modified switches are still not quite at the sweet spot for switch stiffness. (Modified clicky switch is still slightly too stiff, and the modified linear switch is still slightly too soft, for my taste.)
Can I have an exact specification of the Alps springs?
Just measure with some calipers.