If Rondo's pictures are accurate, your bass will have standard bass type tuners as opposed to skinny post guitar tuners. If this is actually true, then pretty much any bass string can be cut down to fit that bass.
I don't know of any flatwound sets (If anyone does, PLEASE enlighten me - it would make my life simpler) but piccolo gauges are typically around 0.020, 0.030, 0.040, 0.050 - just a general guideline. you may be able to go slightly heavier if you need to use a particular string to make things work, since you have a short scale.
juststrings.com has a good selection of strings in both sets and individuals. If you search for piccolo to verify the gauges you need, you will find all the sets are roundwounds but it is a starting point.
Another way to is to figure that your new E string will be approx the gauge of a standard D string or slightly smaller and go from there - you will just be tuning that string up a step and moving it up a couple of notches in the bridge and nut - please perform the physical actions in the reverse of that order

. Same thing for your A relative to a standard G string.
The issue with flatwounds (chromes for example) is that there are relatively few thinner than about 0.040 available but on a short scale an 0.040 may just work very well for your D string. If it does not, Rotosound does make an 0.030 flat and GHS does make brite flats ground wounds down to 0.027 - juststrings carries both of them. Also, I'm sure I don't know every possibility out there yet.
http://store.juststrings.net/jazzbas...lestrings.html
is the roto for example.
A plain steel string around 0.18 to 0.22 should work fine for your short scale's G. GHS and the others who make piccolo sets make those.
Another possibility depending on the bridge, tuners and headstock would be to try some flatwound guitar strings. They will not work with some bridges due to the smaller ball size and may or may not reach the tuning pegs depending on the particular string's length and the design of the bass. I have found that some brands of guitar strings have a wound area that is over 36" long. The nice thing about this is that some brands flatwound guitar strings go down in the area of 0.022" to 0.025" size meaning that this may offer the potential to have have a wound G and to even get a complete set of flats for a short scale bass cheap.
YMMV of course and I will not be responsible for injury to anyone or their instrument or any bystanders and... in other word use any of these possibilities at your own risk.
Also consider that you got them from an unemployed lab geek who never sleeps.
Peace,
S