From the dimension you gave for the mag length I believe you have .40 cal 10+1 compact?
I have a Sphinx 2000P compact in .40 cal and have had a full size that I worked on for a friend. You have several choices (BTW, the President of Sphinx should pull his nose out of his ass, he doesn't know what he is talking about. Obviously no other mags will fit because they are inferior to his mags):
1. The pre-B CZ mags fit perfectly. Of course there are no pre-B .40 cal mags but the 9mm mags are easily converted by taking about .020" off each feed lip (that gives 1mm wider gap). Some will say this is not necessary but imho it allows the top round to sit a bit higher and they feed better. If a wider gap were not better I doubt CZ, Sphinx, et. al., would waste their time making their's that way. My Sphinx came with a .40 cal mag in the gun and the spare mag in the box (not marked .40 cal) turned out to be a Sphinx 9mm. I widened the feed lips 1mm to match the .40 and I can't tell the difference looking at them under a magnifier nor in function.
2. I have also used the Pro-Mag .40 cal mags for a CZ. They fit perfectly and function fine in a Sphinx. They are heat treated very well, have good springs and have worked fine for me althought I don't rate them as well as CZ factory mags or Mec-Gars.
3. CDNN used to have 2000P mags but they don't show them available for the P any longer. I bought some of these.
4. Best for last: Mec-Gar now has .40 cal CZ mags available. They are superb quality and I have read that they also make the CZ factory mags. I just went down and pulled my Sphinx .40 out of the safe and tried a new Mec-Gar .40 cal CZ mag. The fit was perfect. Fits the mag well perfectly with no slop, clicks right in nicely on the mag release, no interference on the slide, couldn't be better. I would say it is a better quality mag than the factory Sphinx mag and fits better too. I paid about $20-22 each for my new Mec-Gar's but I heard Midway sells them for $18 plus shipping.
BTW, a lot of CZ small parts will fit the Sphinx. I have replaced the slide lock and retainer spring with CZ parts for example. I also replaced the steel mag baseplates with CZ-40B polymer baseplates. They match the front of the grip frame fine and give a bit longer grip and the little finger has a good grip instead of that sheetmetal sticking me right in the center of the finger. Pic of the Sphinx with the 40B baseplate on the mag.