From what I gather, some micronutrients do scale according to your caloric needs (e.g. potassium and sodium), but not all do. Additionally, those that do scale don't necessarily do so linearly, and deficiencies are more likely to occur the further you cut caloric (and micronutrient) intake below 2000.
As a rough speculation (and this is just my opinion, though there may be journals that back it up), the ones that do scale are going to be ones that are involved more in metabolic processes such as muscle contraction and relaxation (as generally the more calories you need, the more muscle you have). As such, stuff like magnesium (involved in muscle relaxation), sodium and potassium (both involved in generating action potentials in neurones, including those that generate muscle responses), and chloride (also involved in action potentials and ensuring fluid inside and outside cells is kept at a healthy ratio) will scale with caloric needs more than other micronutrients.
Now I'll say again, that paragraph is just my speculation, but it seems to make sense. It also leads to the conclusion than a multivitamin (which doesn't contain electrolytes generally) should be sufficient for correcting any potential deficiencies from a lower-than-2000kcal diet on a product like Soylent. But the only way to be certain would be blood tests.