As I understand it the mechanical advantage (MA) of current Shimano dual control levers are not a good match for old style cantilever brakes.
It's a bit of a minefield, Shimano's compatibility charts can be found here:
file:///R:/Downloads/2020-2021_Compatibility_v026_en%20(1).pdf
They list all their STI levers as being compatible with the current CX canti brakes in the range. Older canti's are not listed, but work best with the same pull as long reach callipers like BR-R650, the charts link modern levers to these with a dotted line which means " Braking power is slightly less than standard combination" how slightly less is open to interpretation! There's a couple of levers linked as a perfect match, but I think these are 7 speed (I haven't checked)
Another option is mini V's. Some touring bikes are supplied with these as standard, though the compatibility charts say NO! These for example are advertised as suitable and will be better with modern levers than older ones, though you'll still probably have to run the pads close to the rims and keep them well adjusted.
https://www.sjscycles.co.uk/brakes/front-genetic-mini-v-brake-black/I don't know about modern SRAM and Campag, my only such levers are campag 9spd Ergos, which I've used with mini V's which required frequent adjusting and cantis which don't.