I'll bite in to this one by one, if there's something missing out on what do you want to know then just feel free to ask me all you want.
First off, as for why Sunshine is being played only once while Metalworks is played twice simply comes from my thoughts on making EU more used to the map in general, it's already well proven in NA but keep in mind that the last time Metalworks was played in ETF2L was back in Season 17, in 2014. There's already a lot of information for people to seek further into, but giving it only a single week to play on is not going to make anyone feel like it would be here to stay, maybe it won't. However still, we as admins are completely aware of how Sunshine is already liked in ETF2L and has become one of the Top 5 maps to play in competitive 6v6 as per the poll that we did at the beginning of Season 32 so we do have proven data on that already in our hands.
As to how players are going to make a map veto with this many maps, it can be done with the already existing system that ESEA uses in their playoffs, for the people that are unfamiliar of it it's upper seed to decide who starts, AB to ban maps, AB to pick maps, ABAB to ban maps again with the last remaining map as the decider. Do keep in mind that this is not yet confirmed, we are still able shift around the ban/pick order so that at least teams taking part in the Premiership Qualifiers don't need to suddenly ban Metalworks and Logjam only to play Badlands for the first time in possibly 5 months. Whether that will also remain the same for the playoffs at the end of the season is up to a debate as well, but I don't see this having too many issues as of now.
EoN's #44 post brings up a really great point, I had overlooked this from even being a possibility. I would say expect a new rule update on that matter, most likely to include the first team to win the mid point if neither team has mid point in control even after the time is over, ensuring that round resets do force teams to start fresh.
I've probably said this enough to make it sound like an excuse at this point, but adding in Metalworks is a step towards having a similar map pool in line with ESEA, with Logjam just being an exception so we do not have to end up with a similar mess of opinions Cardinal had brought to us a year ago where the map got a heavy amount of critique that we couldn't give it a second change even afterwards, the fact that the map development stopped for it by that point didn't help that fact either. Personally I would also want Logjam to receive seasonal updates to bring it to peoples liking again like it did for the people that wanted to play Logjam again before it was added in Season 32. But just to touch on to the ESEA part still, we are aware that this will be the last season ESEA will have for TF2 and whether other upcoming orgs wish to alternate the map pool significantly is up to them to decide on, but if they would rather copy the map pool mostly from us then we already have a rather familiar template for NA to work onwards from then.
The reason why testing Propaganda has been skipped over in ETF2L is pretty much my fault, I do believe that the map could very well shape up to be a decent map at the very least in EU, I would be glad to test it out at least once. However before we had made our preseason cup to try out maps in, I got approached by lucrative, a key figure in NA that really wants to introduce new maps to a competitive format and help them succeed in the future. Not calling him out for doing anything bad, rather the opposite because he's pouring his heart into getting a kickstart to these new maps that could easily be ignored otherwise. Anyhow, he suggested for me to try out new maps that had done well in his map testing PUGs with plenty of positive results in some of the ones that were chosen for the preseason cup we had in last week. I would like to note however that Metalworks was not one of the maps lucrative suggested for us to try out, having that included was purely done because of people asking for it to get played in ETF2L. I wanted to add it into the cup to see if the playerbase would be a lot more fond of it now than previously, however had we not added it in I'm pretty certain we would have the same guys asking that why is EU not playing Metalworks still when it has been played in NA for many years already for now, that's not something I'm able to answer to but that's the reason why Propaganda could have been recently played instead. All the feedback regarding how much you want to play it will be kept in my mind for the next time we want to give new maps a similar chance.
Will continue in the post below to make sure I won't get annihilated by any possible character limit for a single post.