Yeah, I would leave Byte 18 alone. If you had the 1K0 BCM I would be reasonably confident that we could figure out (meaning fix) the proper coding if it needed restored. However, since you have the 5K0 Jetta/Tiguan/Eos style module I'm a little concerned. I'd hate to see you invested into a 5 - 10 hour episode ( 255 Dec possibilities ) fixing this if it doesn't work out as planned.
IF you want to give it a shot .. I think the Hex value of 02 would be correct for a NAR style DRL with front headlights only and no rear tail lights.
You could try altering the coding of the RLS for the light / brightness setting, but I don t have one to offer any coding recommendations. That would be easily reversible by pasting the original coding back in (0730AD) unlike the Byte 18 deal.
The freeze frame data isn't so simple on a VW. Unlike Audi, this is a little messy and that's why the dealer tool takes soo long to run a complete scan with the correct (translated) data shown. We're pretty sure we have this figured out but I don't think VCDS users will like the serious increase in basic fault code scanning and communication this will require.