Logic icons should be rendered with white filling
The PNG version of the Logic icon set (/usr/share/dia/shapes/Logic) has transparent background and black border. This give good results on white background, but is unreadable with a dark theme.
Rendering the icon set from shape to PNG with white filled shapes should resolve the issue.
A best solution could be to render them dynamically depending on theme colors, could be a better option (especially for line only shapes), but would need more work.