What you asked is possible (since MIDI notes are just numbers and Max MSP can read and write Clips), but I'm not aware of any pre-made device that works like that.
Perhaps Gibberwocky, but it is for livecoding, probably more complex than you want.
similar to a word processor's "search and replace" function
The Live Sets .als files are actually human-readable gzip-compressed text files, you can uncompress them with 7-Zip and then use an actual text editor's search and replace functions.
MIDI notes are numbers:
http://www.inspiredacoustics.com/en/MID ... requencies
I'd like make every note event that's an Eb an E
Easily done real-time with a Scale device.
Put a Scale device, press "Eb", its respective "square" will light up in the Scale device, move the square up or down the column to the new note you want (1 up for "E" in your example, I believe).
Can also be done with the Key Zones in the Chains in MIDI Racks (more work).
or every velocity that's 65 to 75
Can be done with with Velocity Zones in the Chains in MIDI Racks.
Add a chain to a new MIDI Rack, set it is Velocity Zone to just the 65 velocity, then put a in that chain a Velocity device with Mode set to Fixed and Out Hi set to 75.
Then you need to add 2 empty chains and set their Velocity Zones to cover the rest of the Velocity range, otherwise only the notes with 65 velocity will pass.