Rendering Unicode diacritics doesn't seem to work properly

hello

Attempting to render this to a bitmap results in
[no diacritics](https://media.discordapp.net/attachments/695829366457892994/876279538663960616/zalgo.png?width=676&height=676) bein rendered.

[Relevant code snippet](https://gist.github.com/BenjaminHolland/2703a1cf2a98d4bb9522132d846f19c2)

Edit:
I realize that not all of these are diacritics

Start with the linked relevant code snippet and reproduce the bitmap rendering case shown in the issue, focusing on the missing Unicode marks. Done means the reported Unicode characters render correctly in the bitmap; no repository file or test is named in the issue.

Written by the indexing model from the issue text.