what is the text in your csv file? does it contain the line break tag <br/>? and it is the same when imported in Visionaire? when imported you should not see this tag anymore and just a new line instead.
Since you are using a very old version I'd recommend you to either use the latest 4.x version or the currently released 5.0 RC. In case it is a bug in Visionaire it was probably fixed long time ago.
The text in the csv file (both exported and then to be imported after the translation) is for example "This is the first line<br/>and this is the second line."
Visionaire imports it but it simply hides the line break tag without adding the new line.