For some context, FL Studio had pretty poor plugin delay compensation (PDC). I believe the mixer delay was primarily created to address that shortcoming, with the ability to use that to compensate for articulation attack times being a bit of an unintended side effect. Cubase and Nuendo have some of the best automatic PDC in the industry, so such a feature was never a necessity before. (Of course you can still set delays for hardware devices manually)
In Cubase, track delays should be set at the source (the Audio/MIDI/Instrument track itself, using the Inspector) like Martin said. Currently, you’ll need to use a separate MIDI track for each articulation to compensate for their attack times.
Being able to set delays per articulation using Expression Maps is a pretty popular feature request. You can vote for that and other Expression Map improvements here: Expression Map - Helpful Additions