Mafalda is focused only on the media part and the logic of the load balancing, not on the infraestructure. It notify when new servers are needed, but It doesn’t spin them Up by itself, althought it’s on the roadmap to create a new module to do that.
Regarding heuristics for the vertical scaling, it’s making use of the actual CPUs usage, and algorythm try to concentrate Consumers in the less amount of Workers, reusing current ones if their CPU have still some available cycles.