UA supports text-orientation:upright if there is a vertical line of text to the left where the topmost character is aleph, all letters are upright, and text overflows only past the bottom border (not past the top).

[For the spec as written, even brackets and dashes should be oriented as if in horizontal text, e.g. the dash appearing as a horizontal line. Is this desired?]

There is a cyan border at inline-end. If the cyan border is at the same side as where the overflow occurs, then this UA's behaviour is consistent with resolving sides relative to the used value of 'direction'; and if the cyan border is at the top, then this UA's behaviour is consistent with resolving sides relative to the computed value of 'direction'.

(The two should differ for this case according to css-writing-modes, but not all UAs fully implement text-orientation:upright yet. If the two do differ, then the used value would be the best reading of the spec, and likely what authors would want.)

Result: None of the UAs I tested (Chromium 53, Firefox 45) support text-orientation:upright as specified: in each case, the used value of 'direction' is simply equal to the computed value of 'direction' (i.e. it overflows off the top rather than the bottom), so the css-logical-props question cannot be tested.