I have found issue about default font properties:
Default Font Size
It was been created in 2011 year. There is any progress on it? Can I set default font-size by some way, which would been applied for all texts by default?
I like to share that we have introduced the support for setting the default rendering fonts in Aspsoe.Slides for .NET and Java. Please visit this documentation link for your kind reference in this regard and share with us if I may help you further.