are you asking if the shunt is directional? then no. it's not. it can be fliped either way. but all the wires will still be connected as shown. the placement of the wires is what sets the direction.
or based on that picture you are asking if if matters which side the shunt the battery monitor neg
goes to? of course it matters. if it's on the battery
side the power consumption
of the meter itself is not being monitored or included. which isn't much draw but it's on 24/7 and will add up.
your question of "which side does battery neg go to" isn't a clear question.
I would get rid of all those silly screw connections and do it with proper crimped ring connectors and heat shrink.