Here how I would have approach this.. See if it can help you.
1. Metadata description is added to illustrator graphic using Bridge.
2. Graphic placed in InDesign.
3. Create a Paragraph Style with a named Numberining List with a character style for Fig., add a Nested Styles option for the second bold part ending at a sentence. The main text is Italic.
4. Make a Live Caption setup. Using Description, the paragraph style and put the results on his own layers. Not grouped.
5. If using CS6 make an Object Style with only the Text Frame Option for Auto-Sizing Height only. From the bottom.
6. Place all you graphics in InDesign.
Then when ready...
7. Select all the Graphics in the Link Panel, and choose Generate Live Captions.
8. Then use this Script: "TomaxxiVARIprocessor" - > http://tomaxxi.com/downloads/
9. When executed, the script allow you to convert the specified variables to text, and apply a object style at the same time.
This should allow the nested style to kick in, allow reflow, and also apply the auto-fit text option.
Sure you will loose the Dynamic updating of the "Live" Captions, but if you ever need to redo them, just trash the Caption Layersm and redo steps 7 to 9.