When importing a translated XLIFF file, an error happens and only one scene gets translated

Ok, knowing now that the error(s) are most likely on slide 3 or 4, this is where you will want to start looking.  You're going to be looking for tags in the <target> sections that are closed early or don't quite match the <source> sections.

If you're doing the XLIFF file by hand (using Notepad for example), you can find slide 3 (or slide 4) by searching for unique text so you can search for it faster.

Now it's looking line by line to see if the <source> structure matches the <target> structure.  Look to see if any extra tags got added by accident.

As for when the Storyline forum moderators will respond, don't quote me on this, but I recall they were going to be out on vacation?  I can't remember though if it was this week or last...

FYI - I did write an application that creates properly formatted XLIFF files and uses Amazon Translate to provide the translation.  Unfortunately, I can't tell you the name of the application because it's against forum rules ('self-promotion').  I have some additional thoughts on how I could help but we would have to do that through private messaging / Linked In.