The problem with mixing radial and angular bearings is Newton's 3rd law. In order to produce the preload on the angular bearing you have to have some thrust (or axial) load. This is normally balanced with a similar angular bearing at the other end. However with a radial bearing there's no way to preload the angular bearing without putting an axial load that it's not designed to handle on the radial bearing.

Simple rule, radial bearings are where there's no meaningful axial load on the axle (or shaft), and angular bearings are for when the baring pair have to take combined axial and radial loads or for when zero axial play is called for. The two don't mix well at all.

I assume (though I've never checked) that in Shimano type hubs with a cartridge bearing on the left, and a cup/cone bearing outside the freehub supporting the right side, that the left bearing is an angular contact type. If not, it will probably fail long before the right side does.