More precise \rlaps for the previous MWE:
\hbox{\rlap{\ruledhbox {\transparentgreen\tfx c\symbol{glottalhamzah}c}}%
\hskip-.075em \ruledhbox {\transparentred c\symbol{glottalhamzah}c}}
\hbox{\rlap{\ruledhbox {\transparentgreen\tfx c\symbol{glottalayn}c}}%
\hskip-.075em \ruledhbox {\transparentred c\symbol{glottalayn}c}}
On Aug 12, 2023, 4:11 PM -0600, Idris Samawi Hamid ادريس سماوي حامد <ishamid@colostate.edu>, wrote:
\hbox{\rlap{\ruledhbox {\transparentgreen\tfx c\symbol{glottalhamzah}c}}%
\hskip-.09em \ruledhbox {\transparentred c\symbol{glottalhamzah}c}}
\hbox{\rlap{\ruledhbox {\transparentgreen\tfx c\symbol{glottalayn}c}}%
\ruledhbox {\transparentred c\symbol{glottalayn}c}}
:
Note the \rlap's (see attached pdf): we see that \tfx doesn't scale the \symbol, although \tfa and higher do work.