The bug
Minecraft font doesn't include the ˇ diacritic (caron) as standalone character, but includes letters Č, Ď, Ě, Ň, Ř, Ť and Ž.
:info: VERY IMPORTANT:
This issue is not a duplicate of MC-169319. That one speaks about a different accent, which has already been fixed.
Can you confirm MC-169319 being fixed?