Firstly, thank you for asking before submitting requests. This makes my life easier. Many people don't.
In answer to your first question you can check on the website - when you view a Titan personality by clicking on the file it will have a 'C' indicator at the top if there is a Capture model link present (similar to 'P' for palettes and 'M' for macros).
However, this is currently not foolproof in that it only checks the model and not the modes. This is also true for the indicator within Titan. Due to the size of the library an automated system was initially used to try and catch and link as many as possible which was successful for the most part but for unfortunately for various reasons some ended up without mode links. This would probably explain why some are not working despite patch view suggesting they should. Many have already been fixed but it's a manual process.
The only way to be absolutely certain at the moment is to install the latest library and then patch in a new show. If it doesn't appear in Capture or does appear but doesn't simulate correctly then please submit a personality request or bug report via the website as appropriate. In case you're not already aware please read the requirements for Capture support
here first.
Regarding updating fixtures in a show there is an issue in Titan at the moment whereby it doesn't try to populate Capture after updating a personality. The trick is to ensure the Capture window is open and then patch a new instance of the fixture after they have been updated (for example the MAC 250). This should then force Capture to populate. You can then delete the extra fixture.