Can there be multiple hydraulic systems?
This aircraft naturally has a normal hydraulic system with hydraulic oil as the hydraulic fluid, too, in addition to the fueldraulic one. In fact, multiple normal hydraulic systems. (As anything more complicated than a single-engine GA aircraft tends to have. As far as I know, MSFS doesn’t currently directly support modelling of such either. See Detailed hydraulic system coming? )
The SDK documentation talks about only “the” hydraulic system. And I can’t find anything in the cfg files that would allow you to define several. In the future the sim will no doubt have multiple hydraulic systems that are defined in a similar fashion as the electrical system with its an arbitrary number of buses and circuits or the fuel system with an arbitrary number of tanks, lines, valves and pumps.