Good questions. As you say, age is a calculated field and afaik won't be available.
Either you need to adjust how the DoB field is displayed which may be via js.
Only other option, for display purposes, would be to build (you guessed it) a Drupal view block and show that instead.
None of the extension you mentioned have schedule job or script to fix historical data, we had to write a script to update historical data when the extension was installed, and going forward extension managed to capitalize the name.