Robert,
You are correct that measurement values currently expect a 'single entry', textual or numeric. It wasn't designed to support multiple lines.
What you ask for makes perfect sense in the context where the measurement in fact includes more information and are in fact 'free text' notes.
We are considering adding a new style of 'value' which would support 'free text' as a data entry alternative. It is unclear if that would make the interface unclear, or if there are ways to make the distinction more intuitive. Any suggestions?
Thanks,
Support Team