I have a weird font in certain places of LibreOffice on my Mac, e.g. the row and column numbers/letters in calc or the titles in the options window. Is this the intended font or an error? Can the font be changed?
Thanks & Regards, Chris
Looks like an operating system issue. This might be a starting point font - Weird text replacements on all apps on OS X - Ask Different
Thanks, @EarnestAl, you led me in the right direction.
I tried the hints mentioned there about checking the fonts, but that did not help. However, already in the Font Book, I looked for and identified the font which was used in these places.
The font used in the circled places is a font named “Gill Sans Ultra Bold”. When I disable that font, the font used in the circled places is pretty much the kind you’d expect. Re-enable it again, and the ugly… uhm ultra bold version re-appears.
Not sure why it particularly picks that font over the one it should be using, but I’m living happily with “Gill Sans Ultra Bold” disabled for now. 
Probably best to remove the font and maybe either re-install it, or see if there is an updated version and install that instead. See Install and validate fonts in Font Book on Mac – Apple Support (UK) or change the Mac version in drop down box on page to match your version. Links to removing fonts at bottom of that page.
A quick search on internet doesn’t bring up any substitutes that look close enough to be a near replacement
It looks to me, as if it takes the boldest kind of the font family it can find to render these titles. Just that the boldest kind, in this case, is kind of ugly 
Disabling or uninstalling both fixes it… and, as I said, I will not miss that ultrabold font too much, so, no need for a replacement 