Furnitures contains strings.
Plots contains dictionaries that have strings and cframes.
Messages contains an identifier-number based dictionary that determines if a message has been read or not according to the boolean.
It doesn’t look like it is too large. Generally, you should try to keep it below 4MB, or about 4 million characters when it is encoded as a json string.
As long you aren’t saving information about multiple users under a single datastore key this should not be a concern. No matter what you do you will always be way lower than the limit, unless you want to save something that by nature has a lot of information/bytes. For example serialized instances/builds, images/drawings, neural network weights and whatever else might require large amounts of data to be represented.