For now, you must adjust the size through the ODS style. Here is a simple example:
define style biglabel;
parent=styles.listing; /* or your favorite style */
style GraphDataText from GraphDataText /
You might be looking at the old file, especially if Word was still open when you reran your code. Are you seeing any messages in the log, such as:
ERROR: File is in use, C:\temp\report.rtf.