You could probably shorten the chain slightly. However, it's asking a lot of any derailleur system to cope with big front ring to big back sprocket and little front ring to little back sprocket.
Indeed. I would however suggest that you need to have enough chain to not break things if you accidentally end up on big:big with any system, and ideally have this as a usable combination on recumbents (especially bikes), where chain line doesn't matter but you need a low gear to get moving, and are therefore likely to instinctively shift all the way down the cassette when stopping at short notice.
To the OP I'll note that barakta's Sprint has always been a bit reluctant about shifting to the smallest sprocket. I'm not sure this is due to chain length, though, as we have it set so that it's a bit tight with the boom set for my leg length, and a bit loose when set to hers - about a 2cm difference - swapping between the two doesn't affect the shifting behaviour.
I've also mucked about with cable tension, limit screws, B-tension, replaced the cable and thoroughly cleaned and lubricated everything countless times, to no real effect (though a mucky parallelogram certainly doesn't help). I'm also going to declare the cassette lockring to be Bastard Tight, on the basis that I've never succeeded in getting it off (suggestions welcome, btw).
Unless anyone has any better ideas, I'm prepared to chalk it up as an inherent feature of running a mutant 9-32 cassette...