1) You got that error because you tried building an OS enabled scenario using the stock build-cache-file command. You can't do that (I'm pretty sure I stated this somewhere). You have to remove the reference to the yellow tag, then you may have to hex edit the scenario tag to change the tag reference field to a 'sbsp' instead of 'yelo'.

2) There's tag data already avaiable in the project yellow tag for filling out lightmap data...just use that. It's just manual work. That's as much support you're going to get from me on this multiple lightmap issue.