I don't work in Sermon Editor, it lacks functionality. But I do copy my sermons in for filing/indexing purposes. Now when I copy, it randomly inserts paragraph breaks in the middle of sentences. ??? what's up?
I think a lot depends on what you are copying from and if there is a stylistic change (normal to italics/bold or something like that). I have found that pasting from a website for example, if there is bold text, it would insert a paragraph break at the start and end of that bold section. Why? Who knows, but maybe you bringing this up will help.
I'd gotten used to the bold and italics dropping spaces. I'm copying from Word. Random line breaks inserted into the middle of sentences in both normal and heading styles.