Flavio, quite some time ago I was shooting indoor industrial situations and as it was invariably mixed lighting with at the time common sodium lights mixed with Tungsten not to mention good old fluorescent nearly always in there as well, shooting transparency film was impossible.
Almost always we used colour negative film for these situations, then exposed in the darkroom to Kodak Color Print film, then a C41 process to end up with a nearly (sometimes spot on) correct colour transparency. The colour transparency was needed for 4 colour printing of magazines and advertising brochures and at the time this was arguably the best way to get the required end product looking good; the magazine or advertising material that is.
We tried a few times to utulise very high end colour scanners going straight from a camera exposed colour negative to 4 colour separation printing plates, it just wasn't quite good enough.
Around that time Fuji released their Reala four layer C41 negative film, I had use of it in my country within a couple of weeks of the Japanese release. More or less it was a revelation, the colour fidelity under mixed lighting was unbelievable; just what we needed. We were able to go straight from a camera negative to a Chromacon scanner, which to put into perspective, the complete system cost our company close to $1,000,000.00 for each unit.
As for multiple layers, I think the three colour negative manufacturers, Agfa, Kodak and Fuji all had multi layer C41 technology, some of which went to market. Kodak had a duplication colour film, neither Agfa nor Fuji had one. Kodak's duplication film was three layers of different colour, with each layer having three layers for a total of nine layers. This was explained to me by a visiting (from the USA) Kodak scientist.
So you could be correct about Agfa doing with three layers, what Fuji did with four layers. That said, Fuji's Reala film was a turning point in C41 film and was demonstrably better in mixed lighting situations; they were streets ahead of the other two at the time.
We were a Kodak house, virtually nothing else was allowed or used officially. Fuji Reala was a notable exception.