I've found the KPI card a great way to display text on boards. Unfortunately, these are not editable but look a lot nicer. Depending on the use case you could have entry into a line item and if it needs to be displayed elsewhere you use the KPI card. We have used this a lot for messages to end-users.
Hi @kenzael since your comment has been posted we have now released commenting in the Anaplan UX. You can use this to comment on cards on a dashboard and these conversations are tied to context (with different threads for different intersections of dimensions). We've also just released user tagging so you can bring people into the conversation when you need them. Please let me know if you need any more information - I hope this is useful!