I wanted to point this out as it seems slightly odd behaviour:

Adding Glyphs for which there is already a template glyph present in the font works perfect when “sort font” is selected (it directly puts the newly added glyph in the spot of the template glyph). When “sort font” is off however, it appends the new glyph to the end of the font but also leaves the template glyph in place (with the same name and unicode!). When the font is closed and opened again, the new glyph appears in the right place and the template glyph is gone.

Maybe I’m missing something but I would think that checking whether the template glyph already exists should take precedence over the “sort font” checkbox.