Letters Ǖǖ Ǘǘ Ǚǚ Ǜǜ don't display the diacritic above the diaeresis correctly

[reuniclus]

Problem description
The letters Ǖǖ Ǘǘ Ǚǚ Ǜǜ don't display the diacritic above the diaeresis correctly. Most are moved to the right, but ǚ displays the caron diacritic (ˇ) as if it was a macron (ˉ).

Expected behavior
Ǖǖ Ǘǘ ǚ Ǜǜ should display their diacritics on top of the diaeresis, as is the case with Ǚ.

Screenshots

To Reproduce
Steps to reproduce the behavior:

1. Input Ǖǖ Ǘǘ ǚ Ǜǜ in any program.
2. Change the font to Fraunces

Environment (please complete the following information):

• OS: [Windows 10 v10.0.17763 Build 17763]
• Browser: [Chrome 90.0.4430.212]
• Fonts: [v 1.1]

Additional context
These letters are common in Hanyu Pinyin.

[kenmcd]

It appears that Fraunces only supports 2 of those 8 characters.

The other broken characters are being created by the application.
But something else is going on here.
I copied the characters from the thread title - and they do not seem to be matching.
Regardless most of them do not exist in the font.

[reuniclus]

It seems that is the case. Regardless, lowercase ǚ does exist and displays the caron diacritic (ˇ) as if it was a macron (ˉ).