Norman,
If terminal is ok for you, but studio isn't, maybe you should try the VSCODE Lite terminal.

I'm using: IRIS for Windows (x86-64) 2024.1.4 (Build 516_1U) Sat May 31 2025 13:15:40 EDT
I get the same in Terminal (Telnet) and also in VS-Code Lite terminal:
MSCEME>write $ascii("♥") 
9829
 

HTTP 401 means "Unauthorized" check that the web application /terminal has the correct credentials and correct authentication methods (password, LDAP etc.)
(the /terminalsocket should be always unauthenticated, its the default)
to help you resolve this, you may use auditing, to see if there is a "login failure" when you try to access.

I would day that the bot answer is not relevant to what you asked.

there is no directive to do looping in macro definitions, however, you could look at a directive called #execute where you should be able to execute any valid COS code, but there are some limitations:
#execute | ObjectScript Reference | InterSystems IRIS Data Platform 2025.2