First your regex doesn't match your tags. You need

/^\[%/

at least.

To push an item onto an array referenced by a hash element you need something like

push @{$outer{$tag}}, $full;,

but your snippet is so isolated that I am not sure where "desclines" comes from or is doing, so that may not be quite right.

There's no way to comment sensibly on the rest of the snippet as in isolation at least, it doesn't make much sense.

Maybe that will help.