Build 3.0.0.59 of xlsgen adds support for rendering rich labels in text boxes and vector shapes.
So far only regular text would be rendered. Rich labels include one or more formatting runs meaning that more than one font can be used.
Rendering works with floating text boxes, floating vector shapes, as well as text boxes and vector shapes inside charts.
And it works with XLS and XLSX files.
Rich formatting in text boxes and vector shapes (screen capture from a PDF file generated by xlsgen)