The Generic Profile does not transcode anything. Using it is fine if you only have files in your media library that are supported natively by your Panasonic.
If you start to add files to your library that are not supported by your TV then you will need to use a different profile (for example, h265 video is not supported by your TV, nor is the old DivX codec or some HD audio codecs. You will find files using these codecs will not play on your TV unless you transcode them, which requires a different profile to be set).
If you do need to use another profile, the Panasonic Viera (2013) profile is fine, but you may also want to add your own
Panasonic Viera (2015) profile. Have a look at
viewtopic.php?f=7&t=21909 for my profile and some feedback from a CX800 user.