From my own testing of rocket part, it does NOT matter what the rocket part recipe output is for a rocket silo. In fact, even if you were to set the result count of the output to 50 rocket parts as a result of the craft, it doesn't result in the rocket being done in one craft. It still takes 50 crafts of the recipe to complete the rocket.

So, if you want this to work as you intend, what you need to do is create a rocket-part to rocket-part recipe that crafts nearly instantly, and have another machine actually craft the 2 x rocket parts that you would get out of the input ingredients. It is annoying that the rocket silo works like that.

The other alternative is to make an Aquilo exclusive rocket silo, that has its recipe fixed to the Aquilo rocket parts recipe, but then reduce the number of "rocket parts" needed to craft the rocket to 25. Recipe for that silo could just be a simple conversion recipe.

Can a rocket silo handle byproduct output? The ratios could be kept the same and even add some additional "fun" by making it 1 rocket part product with a 50% chance to return each input.

Or if it is true, just simply set the result to one, and ignore the ratios, but thank you for the feedback, I will take a look into it

I made the bug report, if its a minor bug, then I will drop the result amount back to 1, with lowering the processing unit and rocket fuel ingredients (probably the easiest solution)

You could do what my mod does https://mods.factorio.com/mod/quality-rocket-parts,
and every tick look at the rocket progress and use that plus the current recipe to work out how many parts where created, and then adjust the progress accordingly.

No, I will not, on tick functions can become CPU heavy, which I tend to avoid

Fair enough! I only did it for my mod as I couldn't think of any other way, but I put a setting to control the frequency of updates and let people disable it.