All accented letters have their default look, but if the breve doesn't mutate anything, it isn't
Relates to MC-193223 and MC-169319.
MC-169319 Letters ä, ë, ï, ö, ü, ÿ are included in the default font, but the alone umlaut/diaeresis (¨) is not.
MC-193223 Minecraft font doesn't include the standalone caron/háček (ˇ) but includes letters Č, Ď, Ě, Ň, Ř, Ť, and Ž