That doesn't happen to me, maybe do some troubleshooting?
I'm also playing 1.6.4 packs again. Currently another hardcore BnB run, then Crash Landing. So hard to let go of them.
if you're using the legacy ftb launcher, you have no issues, or maybe it's just if you do or do not have newer hardware/os like win10. dunno, just know this is a known issue (google is your friend). from what I read it has more to do with mojang changing something with the launcher than curse/twitch tho.
tbh tho, I pretty much despise the curse/twitch launcher so I inevitably migrate all my packs to mmc anyways. Getting a 1.6.4 pack tho up and running even with java 8 seems pretty painless as long as u use mmc to create a new instance and just copy the contents over afterwards.
as far as 1.6.4. packs yeah I was just really curious about CL and how it holds up to my perception of time. and imho, like almost all old games, they somewhat fail to live up to what my reality is now of other more modern and mature packs.
there have been a couple packs that have gotten that early game mechanic done almost as well as cl, but they don't suffer from the constant food maintenance and water mechanics plus they have the benefit of giving you more things to do after you get stuff done. for insance, newer versions of tougher than nails has a addon mod that adds some baubles for temperature and water you can make that give you some way to remove the pita of that mechanic after you've teched up a bit. having the mechanic there, but then surmountable later on, to me seems like the best way to reward the player while still putting them under the gun early on, where it shines as a goal oriented objective.
My issue tho is mostly the immaturity (in comparison of newer versions) of a bunch of stalwart mods. I didn't enable eio but I did enable ZA since I feared hqm issues if I did. TE ducts always drove me nuts and having stuffed items made me insane at times over the last few days haha I absolutely love AE2 and all the things that ppl hate about ae2 I love to death. ae1 just seems so simple in comparison and ez mode.
the fact that the dust all around you is not a natural shovel material drove me nuts and for digging out a single cube, I preferred to use an open hand or block of dust to mine it out, vs newer *nihilo's which treats them like sand, etc. excavator ftw tho for doing it en masse but still....
I do miss sfm tho. but you do have some alternatives but not any that are 1:1 akin to it. Saying that, I've yet to use sfm but are about to so that I can get yellorium en masse for a reactor. Like most of my previous playthroughs, as soon as I do that and a laser drill, I'll be done with CL, probably for another 4-5 years lol
as far as BNB goes, I feel no need. there are quite a few packs in 1.10-1.12 that I've played that feel even more bloodthirsty then bnb did and tbh, I've never been fond of witchery.
I still hold regrowth as my most played/favorite pack, with CL a very close second. bnb gave me alot of fun times back in the day but I've played a bunch of 1.7.10 packs and others that have probably crept up to round out my top 5-10 packs. overall, nostalgia is trumped by features from my viewpoint.
with all that said tho, alot of those packs wouldn't exist w/o some ideas forged into your mindset like CL did. I definately give iskandar/shane credit where credit's due. it was a fantastic pack for the time.