One eveing in early 2Q2022, I was reviewing posts in my blog - when I was reminded of the clue about Louis Goetz's passport application in 1896 (See this post).
I went to the FamilySearch catalog and typed in Germany, Sachsen-Coburg-Gotha. One of the reference books about the area that came up, with a digitized version, was:
"Geographical names in the duchy of Gotha and the Thuringian forest. Indexed."
"Germany, Sachsen-Coburg-Gotha - Names, Geographical"
I searched the book for a map and then spent an hour or so looking for the village "Ober Mallia" aka "Ober Mehler".
I found it!! It is northeast of Muhlhausen (the geographic center of Germany). This graphic shows page 610 with a focus on the detail around Ober Mehler (abreviated Ob. Mehler). 
From the index, page 585, it says Mehler, Ober information is on page 389 (E2).
I did a little research about the area ... just scanning some pages in Wikipedia. One item of note was this Wikipedia page on dialects in the area. I was trying to imagine someone saying "Ober Mallia" ... and how that would sound to an American.
Our Goetz ancestors' dialect details may shed some light on this since "{t}he Thuringian dialect is characterized by a rounding of the vowels, the weakening of consonants of Standard German".
Their dialect is: Nordthüringisch / North Thuringian: around Mühlhausen and Nordhausen
More to research ......
Another book that might be of interest:
"Collection analysis report: The Thuringian states : Summary of Family History Library microfilm holdings"
References:
1. Die Flurnamen des Herzogtums Gotha und die Forstnamen des Thüringerwaldes zwischen Weinstraße im Westen und der Schorte (Schleuse) im Osten; familysearch.org
2. Collection analysis report: The Thuringian states : Summary of Family History Library microfilm holdings; familysearch.org
3. Wikipedia, https://en.wikipedia.org/wiki/Thuringian_dialect
4. Wikipedia, https://en.wikipedia.org/wiki/Saxe-Coburg_and_Gotha
5. Ober Mehler in Meyers https://www.meyersgaz.org/place/20374051