Don't know what they are referring to as "Bronze Brazing". As with "Silver Soldering" It is often a common misuse of the terms. As it is more a temperature dependent procedure. Since brazing rods are mostly a naval bronze/ silicone bronze/phosphorous bronze alloys.
If what you are talking about is the Brass/yellow/gold looking brazing filler metal whether it is on steel or other.
Soldering takes place below 840'F (450'C) filler metal meting temperature.
Brazing is above 840'F (450'C) filler metal melting temperature.
Both of the processes, depend on the use of fluxes and non ferrous filler metals to wet the metals surface. For the increased ability for capillary flow, which draws the filler metal into the joint.
There is a process that is called braze welding, which doesn't depend on capillary action, but the use of filler metal to fill in joints designed like those for Oxy/Act welding. It is used for mostly cast iron cracked or broken parts.
It is welding without melting the base metal, lower temperature and therefore less distortion of the part.
The short answer is that other fuel gases,instead of "Acetylene" Natural-gas, Methlacetylene-propradane stabilized (MPS MAPP gas) Propane, Hydrogen, and the proprietary gas mixtures that some supplier sell.
They all can be used for soldering, brazing, pre heating and cutting(oxygen). It will depend on the type of torch tip design. and whether it is air/fuel and oxygen/fuel. But that's another whole can of worms and misinformation
http://madmodder.net/index.php?topic=2679.0 here is info on silver brazing. Is more info on silver brazing
Just a side note, the reason you can not ferrous weld with any other fuel gas/oxygen mix is that only Acetylene/Oxygen mix can truly achieve the neutral flame so the weld/filler molten pool isn't contaminated. And end up with a substandard weld.
If you are looking for a color match to the base bronze you may have to try a number of brazing filler metal alloys.
Crown 125 or 125FC is a general purpose
Royal 130FC-P
Crown Sil-Cop 0 Close to Harris 0 ) leaves sort of copper color needs Crown 45 flux(brass and Bronze) The favorite of heating and cooling copper/copper
Crown Sil-Cop 5 Crown 45 flux
Crown Sil-Cop 15 Crown 45 flux
There are others and other brands, the flux is a branded generic type flux temperature range is 1,000'F to 1,600'F #45white the #45black is a higher temp flux.
Hope this helps I will try to answer an more questions you have.