Supposedly the bug - “Fixed a bug causing fonts with no “regular” variant (such as Bookman Old Style) to revert to another variant such as “Bold” rather than the expected “Light”.” was fixed in the latest update in January. However, it still acts in the same way - reverts to a bold variant.
Thanks. This was fixed previously for the 1.7.1 update, but recent changes appear to have affected the font handling so it’s not working in 1.8.5. I’ve put it back on the list for correction.
Until we’re able to re-address this, try applying the font from the Fonts dialog (Format > Font > Show Fonts) rather than from the format bar. That should give you the correct list of variants, and in my brief testing in 1.8.6 choosing “Light” did retain the proper weight in the editor rather than switching to bold.