This project shows how to MIDI map TEMPO encoder and NUDGE +/- buttons of AKAI APC40 to Drambo. You need Mozaic app with my script loaded and e.g. Streambyter (free), or any other app to achieve MIDI loopback. Simply run Streambyter in the background and make sure it is set as MIDI output for ouput from Mozaic (this often switches to “Drambo” by itself).
Also in Settings > MIDI Input, Streambyter has to be selected as CONTROL (no need for TRACK and CLOCK) and APC40 MUST NOT be a CONTROL. Since we need to transform messages coming from APC40 and send it back via Streambyter, you now need to map all MIDI over Streambyter, otherwise Drambo would receive messages from both sources and got confused.

For more info about MIDI loopback e.g. here: https://wiki.audiob.us/doku.php?id=auv3_midi_recording_workarounds#drambo

Background story:
This is a workaround for 2 Drambo bugs on BPM MIDI mapping:
1. Relative encoders on e.g. AKAI APC40 send values >0-64 to increment and >64-127 to decrement. This option actually is in Drambo mappings, but does not work correctly for decrement (jumps directly to the lowest value).
2. BPM mapping in Drambo seems to not work with incremental encoders at all. It always jumps between maximum (20) and minimum (200).

The only way to currently set BPM via MIDI is by absolute control, which is also not optimal, since the range (200 – 20 = 180 BPM) is higher than MIDI values resolution (0-127). Thus some values are rounded and therefore some BPM values are skipped. But it’s still useable for e.g. gradually slowing down / speeding up.

Tempo NUDGE +/- then simply temporarily increases/decreases tempo by 5 BPM. Useful for matching a beat to external source like e.g. a record playing from turntable (or if you simply don’t use any form of sync and just set the same tempo and need to “nudge” the beat to correct position).