In my experience with compressionless housing, the tight bend such as under the bar tape really only affect how easily the inner cable slides. With the tight bend, the compressionless housing squishes to an oval shape & pinches the inner cable. The coiled shortie sections made by Jagwire are a good solution if this proves itself a problem for your particular installation.
For short sections such as the top tube cable stop to the rear brake, I find that most often it will ovalize & pinch as above, gumming up the release action of the brake spring. But, with a few firm brake applications, the short section of housing can then be removed & the ends of the cable can then be trimmed up square. (The inside & outside of the radius are different lengths. It takes a firm pressure to move & equalize the individual linear strands.) After the additional rework, the housing & brakes work as expected.
For a folding bike, just keep your cable radiuses large at the fold & don't expect the brakes to release well while riding it in the folded configuration.
You'll be fine.