Intensity bit issue on Epson Equity LT286 LCD

[freakedenough]

I have an EPSON PC AX Portable / EPSON Equity LT-286 and it comes with an issue how certain colors are displayed on the internal display.
It looks like that the insensity bit causes the issue as it is always on for background colors, thus the light gray background color of the editor menu is drawn in white. Bad if the highlighted text is also white.
There are DIP switches next to the LCD screen connector which allow me to choose between 4 modes:

• B&W, which adds a black background to text with intensity bit set
• Two GRAY SCALE modes, which looks identical to me
• The fourth USER DEFINABLE option looks like B&W but with reversed colors
• On the internal display, text with intensity bit uses a different, thinner font

None of these are really satisying if you look at the pictures below. As if the display can only display 8 colors (shades of gray) and struggles to achieve a minimum of compatibility with DOS. What does the switch option "user definable" mean, what and how I can define something? BIOS offers no options. The original disks that came with the Equity are here, https://archive.org/details/epson-disk-images, but I found no extra tools on them related to the internal display. Compaq Portable offered tools such as ADAPT.COM and CHARSET.COM to fiddle around with gas plasma display colors and fonts: https://en.wikipedia.org/wiki/Compaq_Portable_386#Software ; did Epson ever provide something similar?