I can only add to your frustration. The 190E 2.3 is (or was) a US only vehicle. Someone would have to do a lot of manual work to see if parts can be shared between a 190E 2.3 and your 230E.
My advice would be to have someone in another country check for parts compatibility between your car and an 85-up 230E (W124), and provide you with the part numbers. There's a strong chance you can find the parts in the US if you provide a part number. If the they can check for 190E 2.3 compatibility, so much the better.
Another avenue would be to consult parts catalogs of foreign after market manufacturers. If they show the same replacement part numbers for the 190E 2.3 and your 230E, there's a good chance the 190E 2.3 part will fit. I know Koni (shock absorber) catalogs list nonUS applications. With any luck, a Beck-Arnley (sp?) catalog might do the same.
I've been trying to check http://www.haynes.co.uk
for a manual for your car but he website's been down for the past couple of days. I know they have a W123 250 & 280 manual that's different from the W123 280 manual available in the US.
I envy you. I went to see an 84 230E for sale in my area. Beautiful dark green, AT, fabric seats, manual sunroof, rear headrests... everything a car should have. The minuses were oil leaks everywhere, a clunky transmission, roll-up windows and electric door locks. I couldn't ascertain that 190E 2.3 parts would work so I passed on it.
Good luck with your car.