And that assertion is false. Your so called workaround is the correct way to create custom instruments (except you need to follow through and to connect your new instrument to its correct sounds)
The screenshot is how Tchaikovsky notated his 1812 Cannons. It is certainly not a ‘hack’, though modern notation would probably place it on a one-line staff.
My irritation is caused by posters who, without foundation, make assertions like…
and
Both of which I interpret as “I’ve not had the patience to read the documentation, nor learn from experts”. It is always better to ask first how something can be achieved before rushing to the conclusion that it cannot. That way, in my experience, you will get prompt and expert support from this dedicated community.