"No modern support. "
They literally have put out everything they could on Switch, right around the time the other versions launched starting from the end of 2017. The only major games that skipped this were MVCI, MHW, RE2/3, and DMCV. All of those being huge, massive games that wouldn't run properly on the Switch in the slightest. Yet their smaller games like Mega Man 11 and Shinshekai (The latter being console exclusive), along with every single compilation they made (Disney Afternoon was only skipped since it came out right after the system launch and was in development before the system was even fully a thing, there was zero chance that thing would see a launch on the platform so early in its life with how little time the devs knew about the platform)
I assume you're referring to MMLC2 and all their random ports the past few years like the old REs/Okami HD. MMLC2 launched in mid 2017, and was likely not considered for switch at all due to the timing of the system. (The fact that the game's code notes plans for a 3DS version, and NOT a Switch port, means that it definitely wasn't in the cards until a lot later) Okami HD on PS4/XB1 was also likely planned long before the Switch focus set in. It's not unusual for a dev to be tepid on a system especially when they got burned hard on Wii U with MH3U.
DMC is definitely the most weirder case of them all, but I say that was likely due to the director of the series clearly doubting Nintendo fans would even like such games, if his comments about Dragon's Dogma wanting to do well before they'd bring over DMC are apparent. I'm expecting they'll bring over 4 to the system as well, but not 5 unless there's massive scaling back.
Less debatable but that's unfortunately an annoying deal with a lot of switch games due to the outrageous cart prices leading to a lot of devs just not bothering with big carts. Add to the fact multi SKU carts weren't a thing until last year and it would make their early compilations literally impossible to put on one cart. That's why they had to split XC up into 2 carts in Japan and make the combo pack digital only. I do think it's dumb that the MSRP for those RE bundles are $60 each when they're super cheap everywhere else, however.
"Constantly saying they'll support Switch when it proves itself, which it has time and time again. But nothing has come of it."
Except they literally did. Their weird SFII HD Remix port sold well, which is what they were banking on (Why? I guess to try and see if the SSFIV3D magic would happen again, which led to them putting MH/AA stuff on the 3DS), and then later that year they started doing things like MHGU and announced the MMLC 1/2 deal, along with XC and 11. Literally every single one of their lower-budget and smaller scale games that could work on switch, has come to switch day and date with the other platforms after 2017 (Onimusha Warlords being the first example), and they're even porting older stuff to the system that they could have easily not bothered with.
The major thing about Capcom however, is that unlike Square Enix who makes tons of smaller scale games like the Romancing Saga ports, the Trials of Mana remake, Spelunker Party,, and Tokyo RPG Factory's works that can easily run on switch and come out day and date, they pretty much have ignored all smaller scale projects for a good while now, or put them exclusively on mobile. They don't have any new Ace Attorney games in development, which is weird since they were full force on the 3DS, nor is any compilation of 4-6 in sight despite rumors, nor do they seem interested in a weaker MH game with World being a megaton hit.
All Modern Capcom has really done lately is focus strictly on AAA games and compilations. And if the Switch can't even manage to run a game like RE7 without needing a cloud version well, then there's no way in hell RE2R/RE3R will be ported, nor would anything like MVCI or SFV without downgrading. Thus, unless they make something 100% exclusively for Switch or a lower budget game like a Mega Man/AA title, there's really nothing they can do besides throw up ports from last gen. The fact they even made Shinsekai a console exclusive at all is pretty surprising, and I wouldn't be surprised to see the TEPPEN card game get ported from mobile as well. Really, it just goes to show that their output in general has been a bit slower than it used to be, since when you peel back all their megaton games, they don't have much besides compilations.
I think it's time they let their B teams work on more Mega Man/Ace Attorney titles for all the systems instead of focusing on milking RE games until people are sick of the franchise.