I think you have the common misconception about the DK effect, which is incorrectly summarised as "unskilled and unaware".
There is also the other end of the scale where "skilled and unaware" occurs: people under-assessing their skill (presumed that this is due to judging that most people also have similarly high skill levels).
I think your two "cultures" would shift the self-assessment line up or down on the graph (constant), but not affect the slope very much (multiplier). The line shape or line slope must change somewhat since values are limited (between 0 and 100).
There is also the other end of the scale where "skilled and unaware" occurs: people under-assessing their skill (presumed that this is due to judging that most people also have similarly high skill levels).
I think your two "cultures" would shift the self-assessment line up or down on the graph (constant), but not affect the slope very much (multiplier). The line shape or line slope must change somewhat since values are limited (between 0 and 100).