Briefly: usually we type comments in the Post Comment window and leave the drop-down box between the Preview and Post buttons at its default position, Auto Format. The Scoop HTML parser then adds stuff we don't need to bother about, like line-breaks, paragraphs, etc.

If we use table tags to produce the two columns, the Scoop parser (why I don't know) adds blank lines at the top and buggers things up. So we have to choose HTML Formatted instead of Auto Format. The whitespace then disappears.

I must write this up, collating the experience of those who've done the bilingual columns, and put it in the User Guide.