Error generating locales with newline in messages

I'm trying to generate the locale from the json files, some of the messages should be multi-line messages.

No matter which encoding I try to use for the newline (`\n`, `\\n`, `\\\\n`), I always get errors:
```
error_unexpected Could not format because the source could not be parsed:

line 79, column 54 of .: Unterminated string literal.
╷
79 │ 'alert_err_prj_connect': 'Cannot connect to project:
│ ^
╵
line 80, column 10 of .: Unterminated string literal.
╷
80 │ \n@error',
│ ^
╵
```
for a line
```
"alert_err_prj_connect": "Cannot connect to project:\n@error",
```