The ideal place to ask questions or submit bug reports about Dialogizer is the Dialogizer thread.
Rich text is represented as a table. While the "," operator applied to a pair of strings will form a list of strings, it will concatenate the rows of a pair of tables into a single table. We need to be a little more careful when we want to create a list of tables.
The "list" operator can solve this problem; it wraps any value in a length-1 list. The "," operator will join those length-1 lists together instead of the values they contain. Try constructing your list of choices for dd.ask[] like so:
(list field8.value),(list field9.value)
If the only special thing about the rtexts is the use of a single particular font, you could alternatively give the choices as plain strings and set the "bfont" option when you set up dialogizer; this will apply the specified font as the default for all the dd.ask[] choices:
o.bfont:"swedishFontName" dd.open[deck o] ...
For general dialogs there's also "tfont" for the default font of the body text in dd.say[] and dd.ask[] boxes.