Q:
Is there any way to change the Unicode value of the particular glyph in a TrueType font, so that when I export the font, value will also be retained?
A:
The font of the text you’ve highlighted is a subset of a Type1 font. According to http://xodo.com/view/#/collab/587e133b-3d70-4205-b7d8-614a7b3fa8af, section 9.6.2.1, you could add a stream called “ToUnicode” to the font, containing a CMap file performing the mapping.