I don't see how CoolTerm can handshake, since the sending mechanism is a device I built and it doesn't shake. Both CoolTerm and my Xojo project receive the same Bluetooth feed from the system. I just checked ... I have Flow Control unselected in CoolTerm. And, my data feed is now waiting half a second between groups of 15 bytes, so it's definitely not too fast. Something else must be going on in my Xojo code.
When I run the serial terminal project generously shared by Langue Rodriguez, it reads the first 3 or 4 lines correctly, then displays nothing more. I presume this is because it is getting characters with a value of 00 and E0 and doesn't show them. So it appears that his code has the same difficulty as my own.