Hello. Thank you for contacting the Toolset support.
Well - Glad to know that you find the way how you can add the custom field filters.
Regarding filtering the view by repeating field group fields is not supported yet hence its limitation for now.
This feature is set to publish with the view's 2.7.3 for now. We are already running with the views version 2.7.2, it looks like views 2.7.3 will be the next major release and very soon.
Please make sure there is no ETA on it and it may happen that it will not be published with 2.7.3 without prior notice as its totally depends on our Devs predefined priorities and available resources. I would suggest you wait a bit for this feature until its published.
Just wanted to update you that the feature "filtering the view by repeating field group fields" is set to publish with views version 2.9 in near future.