Using valentina_0.7.0a-20190103140932_10.12%2B_64bit-OSX.dmg on macOS 10.14.2 (18C54) Mojave.
If one's interface in macOS Mojave is set to native dark mode, Valentina will show an incorrectly dark interface even if the internal setting is not enabled.
When the internal setting is enabled, two issues become apparent:
1) The point names are white initially only to become black after a mouse cursor passes over them and 2) The black lines are very hard to see.
Normally, one could disable the dark mode in Valentina and use the normal 'light' interface but that does not work on macOS Mojave.
Attached screenshots show the behaviour more closely.
1) When Valentina is in dark mode, set a colour palette that allows better visibility of 'black' lines. Turn black to white for both black lines and point names. Leave hand-picked colours as they are.
2) When OS is in dark mode but Valentina is not, allow a 'light' palette for Valentina and not pull it from the OS as that won't produce good user experience.