Looking at that link, it appears to still be in very early development. It states directly that it is not yet stable and breaking changes may happen with updates. Perhaps IC2 Experimental has always been this way, but I still get the feeling that this isn't ready for use yet. But yes, I do stand corrected about no official IC2 versions existing for 1.19.2 besides IC2 Classic.
I'm sure I'm using IC2-exp rather than the classic one. I also tried the latest version (industrialcraft-2-2.9.24+ex119-1.19.2-forge.jar) but blocks were still lost. I hope a newer and more stable version could solve this. Thanks for your help!