With the help of someone on Rotax-Owner.com it was determined that the fuel pump is this model:

Pierburg Model E1F-7.21440.78 and the brochure for their line of pumps is here.

So, the verdict (matching the info from TAF SA tech support) is the pump should be tested to 1.85 bar, which is 26.8 psi (I don't think a little more would harm it as the Rotax docs mention 2 bar (29 psi) as the max reverse-bias pressure and a burst pressure of 5 bar (72.5 psi)).