I believe a number of German enginner units also has GL instead of satchel.
There is no requirement for engineers to have either flame throwers, or satchel charges. Their primary role comes from the unit class, and is mine removal.
Of course they can only have grenades but the usual package is flamethrowers and satchel charges for most heavy pioneers.
I thought maybe the oob designer mistook geballte Ladung(Grenade bundle) for Sprengladung(Satchel Charge) and now the bulgarian pioneers only have grenade bundles instead of satchel charges.
I had a look at this and it does look like this is the result of a cut and paste error for one of the units as "84" is a much used spot in the weapons data lists for Satchel Charge. It's on the list to look at next time we start work on the game