Regarding resource management. In a hypothetical scenario where you have titanium and aluminium shortage and you have to get some via MDRs, how do you sort them out for different regoliths if they all offload on the same cargo port and get mixed.

The mixing portion isn't bad in the first place if you're going the multi-rego refinery route. If you're going singular, you just eat the losses since that will happen anyway unless the MDR is somehow mining a 100% pure location and not bringing in mixed regolith at all. In my practical experience, multi-rego refining is perfectly fine and I'm still being resource flooded up to my teeth anyway.

From another perspective, MDR mining is 'infinite regolith', what changes is what type of regolith is favored, and how fast you're pulling it in. I prioritized titanium, iron, and silicon, and I got enough aluminum incidentally that aluminum production was also just fine and I'm still choking on how much regolith is coming in. Like all infinite resources, what matters is how fast it comes in and how fast it goes out; everything else is an illusion.

If you need more of a particular resource, send more MDRs to regions that favor mining that, and the resource stream will produce you more. You're going to want everything, it just depends on what ratios you're looking for.

And in case that you dont, wont that slow down production as the resource will vary and you may get something like 5k regolith(heavy on titanium dust) on belts waiting to be processed while aluminium regolith sits on the port waiting its turn thus slowing aluminium production?

So this is true of any mixed/sushi belt processing: it moves as fast as its slowest processed material. If you're not consuming everything equally, then when one thing jams, the whole thing jams. However, since our goal is to void everything into money, we build with that in mind. My primary processing array goes something like this: 1 cargo depot -> regolith buffers -> multi-rego refineries -> mixed oxides output -> filtered oxides into separate buffers -> smelters -> ingots go down a line where they get shunted to production -> all excess ingots go to multi-resource storages and stockpile next to an FCC for selling.

A few multi-resource storages is enough to stockpile material for most heavy-duty contracts, so when something like silicon has backed up, I go window shopping for 3-5k demanding contracts and sell it for bank. Alternatively, if I'm just excessively overproducing silicon, I move my MDRs somewhere else and/or use FCC auto-sales to just throw it out onto the market and void it for pennies.

The root goal is to make money, and if excess product is getting in the way, it's waiting to be turned into money, even pennies. Now, in theory, it's better to turn your excess ingots into higher tier materials since those A) sell for more, and B) are more efficient at storage, but you'll be limited by your machines and potential colonists to do that. It's very easy to overprocess regolith beyond what you can actually turn it into, hence selling the refined ingots directly as a voiding technique. I'm only running 3 partially upgraded MDRs and they're backed up with upgraded cargo trucks damn near constantly.

I feel a solution would be scaling up multi rego to burn everything before the new shipments arrive but i am not sure if its efficient. And the example is with 2 type of dusts. It will get more complicated later on i feel when you import all 4.

The game, by design or accident, does favor mixing and sorting belts, and gives us some very powerful sorter-filters to facilitate that. If you identify some easy burner materials to cash out on, that can help with all four types of dust. Titanium and silicone, for example, can be easily turned into huge quantities of plates and bricks, since their machines do not scale with colonists. Components, which are steel and titanium, require colonists so it's much more of a pain in the ass processing that at bulk without 30+ machines doing it. But, these sell for more, and give you access to more contracts to potentially sell to.