This is similar to the problem I was having with black text in library items changing to red. I also get text-type library items (little oval bursts with text in them) starting out in the library in Helvetica font and coming out when dragged to a new document in Hiroshige font. I thought this was a style issue so I selected the burst text, selected "Break Link to Style" from the Paragraph Styles context menu, so that the only formatting on the burst text was the Helvetica font, centered, size, etc. Updated the library item. Then I drag this burst into a new document built on a different template, and the text has turned to Hiroshige again even though it is no longer associated with any paragraph style. Why does it do this, and what can be done to stop it?
One way this will happen is if you create a library item, and then go edit the [Basic Paragraph] paragraph style sheet (change the font) and then bring the item in from your library. Strangely this does not seem to work if you change the point size.
Take a look at my reply to "Paragraph Styles" 3 posts down which may help.
So what you're saying is that the "Break link to style" command, while it seems to set the text to no style at all, does NOT actually free it from being affected by the Basic Paragraph Style? This seems like a program bug. I suppose one way around this would be to create my bursts in Illustrator and save them as vector graphics instead of text; but part of what makes the bursts useful is you can edit them to change the wording to meet new situations.