I normally do not use the gallery, but have saved a few things to my library before and know the tag you speak of. The last house I built it didn't show me the option of what packs were used in the house build.
I think this may be a bug. As I'm not seeing the part where it tells you what packs have been used in the house. I'm not sure what to do about it other than report it as a bug in hopes it gets a fix or work-around.
Please Help Us Report Bugs On AHQ Forum (Where & HowTo)
http://www.carls-sims-4-guide.com/forum/index.php/topic,21467.0.htmlIn the meantime you could note what packs have been used in the house, and put it in the house's description.
If anyone has anymore information on this bug, please let us know!!