This is expected, as components attach just like they would using mark attachment (and thus not contribute to the advance width of the base glyph).
Use #entry
and #exit
anchors instead:
(Also, using the “entry” and “exit” names instead of a generic “connect” allows you to chain components. For example, add both an #entry
and #exit
anchor to _smart.n-second-stroke
and now you can create an m
from a stem and two consecutive acres.)