My guess and it is only a guess without knowing which pipes have been bridged is that the previous owner had a leaking heater matrix. The car I just scrapped had that and while I sourced a new one I inserted a3 inch length of half inch copper pipe into the connectors where they come out of the bulkhead. Two one above the other in front of the driver on a UK car.

When you get a new HBV get a a VX one not a pattern one.

Matrix change is a crappy job, even the 'cheat' way, but don't despair, it may be the other way around.

The way I see it, judging by what you've written, what's been bypassed is the HBV, not the matrix.
The fact that you are getting any heat at all in the cabin supports this idea.  If the matrix had no coolant flow, you'd get no warmth at all.

So I'd guess that the HBV has been bypassed because it was leaking. 

The fact there isn't much heat may indicate that the matrix could use a good flushing out.  Worth doing this while changing the HBV anyway.  Guide in the Maintenance Guides section

Photos of what you have when you have fitted the new VX HBV will help