Limiting the number of processors will make the game even more boring. Because there will be one better way to strengthen. And it will still be through multiplication.
Banning bonuses won't help much. Put ten splitters after ten multipliers and you will get an insane multiplication factor, because only one out of 1024 tokens will reach the end. How much there will be for the rest, I'm even afraid to count :)
In fact, I remember several such games offhand. One contained chips with limited capacity and wildly rising prices for each next part of each type. Plus the tricky logic of the work. The other one came out recently, it was necessary to get an exact number and there was a restriction on operations and location. But I recommend that you look at Assembly Planter. Where this very good idea of yours is revealed.
If you want simple and inexpensive solutions, then you need to change the logic of the processors. The adder is essentially useless. It's easier to take one token and multiply by two than to take two tokens somewhere and add them up. Until the adder does something else useful, it will remain unnecessary. The multiplier is an obvious record holder. We need some kind of comprehensive system that makes us use more than just multipliers. While she's gone, everything else is a meaningless fuss.