I wouldn't use the gerund in the first with 'by'. I would say 'set great store on displaying humility' or 'by humility'.
With the second, I think you can say 'steer clear of doing something' as well as 'of + noun', so I wouldn't mark the second wrong.
'Bold relief' exists, but the sentence doesn't sound very natural to me. Firstly, 'more common with' doesn't work, and the comparison doesn't work very well- it is mostly used literally, and when it is used figuratively, I think it tends to be used more in the positive to display a contrast, rather than its absence because the use of relief is to povide a contrast.
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