You would want to apply the rule to .ace-tm, not individual tokens - there is also an element somewhere that Ace uses to calculate font dimensions.
If you want to set the font name only for GML files, you could add a filter like .ace-tm[file-kind*="Gml"] or anything (check the inspector for what fields it has).
But also, if you are doing this locally, you could very well install the font on your system and set the font name in Ctrl+,.