XnSketch 1.20, libicui18n.so.54

[sjsepan]

tldr;
Missing 'libicui18n.so.54' on start in Linux Mint 20.2 (Cinnamon)

Downloaded XnSketch 1.20 today and extracted and placed into /opt/XnSketch.
Followed advice in README to copy .desktop file to /usr/share/applications. (it said 'XnView.desktop', but I used appropriate name in bash cp command: 'XnSketch.desktop'.)
Checked .desktop file and changed references to .sh and .png from /home/pierre/Desktop/XnSketch to /opt/XnSketch.
Running by clicking desktop file shows busy cursor for a few seconds, then default, but no app. Running .sh file in bash shows error:

username@pcname:/opt/XnSketch$ ./xnsketch.sh
/opt/XnSketch/XnSketch: error while loading shared libraries: libicui18n.so.54: cannot open shared object file: No such file or directory
username@pcname:/opt/XnSketch$

File is not present in XnSketch folder nor on my system. Version 56 is present under /opt/XnView/lib and 66 is present under /lib/x86_x64-linux-gnu.

sys info:
https://termbin.com/yszy

PS - was not much activity in the 1.20 announcement posting.php?mode=edit&f=81&p=172985, so reposted as this new thread