Mahjong question

[Talilover]

So I'm kinda at the cusp of 100% on this game and mahjong is one of the final hurdles for me (because who actually willingly plays mahjong) and after reading a bunch of guides and watching some vids I THOUGHT I had a decent understanding of the game.

The goal is to make a hand consisting of 4 groups of 3 and 1 pair of 2 (the groups either being a 3 of a kind deal or a straight kinda and with the pair being 2 of a kind), or at least that's the most straight forward hand and the one I usually shoot for, and doing so has won me a couple matches

Where things are getting pretty ♥♥♥♥♥♥♥ muddled for me is "melding" (using your opponents discards to form groups) and why it seems to actually just ♥♥♥♥ me over. Idk how to post it here (if you can) but I took a screenshot of what's got me confused, here's the gist tho-

Using melds I have made 3 groups of 3 and in my actual hand I have another group of 3 and a pair of 2, so what's causing me headache is why TF the game isn't saying I have a winning hand, what little ♥♥♥♥♥♥♥ tidbit of information am I missing that makes my hand invalid?

thnx for any help (from the 20 or so people who actually bother with this minigame ig)

[Latency]

The game is a little inconsistent in the rule terminology, but to me "meld" is just a term for a set of 3 tiles, either a triplet or sequence of 3 numbered tiles in a row (straight). If you steal a tile from an opponent to create a meld it is placed to the side face up, cannot be changed, your hand is no longer "concealed", and you can no longer declare riichi.

Once your hand is no longer concealed you lose a significant number of options to win. If you look through all the winning hands in the instructions many of them require concealed hands to count, or have a reduced value if your hand is not concealed. Additionally most of the 1-han hands (easiest to get) require a concealed hand to even be worth points so if you steal none of those will be valid ways to win.

One other thing to consider is the "2-han minimum" rule. If this is turned on, there are VERY few hands that can win without being concealed.

In general it is not worth stealing unless doing so gives you a definite scoring hand (Dragon triplet, seat/round wind triplet or something better like a flush) or it is very late in the round and you expect a draw, in which case you want to have the best non-winning hand you can to avoid losing points.

Finally there are a couple of odd rules about Ron that not everyone pays attention to that can cause you to be unable to win. First, you can't win with Ron by stealing a tile you have discarded in the current round. This is rarely an issue, but it's possible to discard a tile very early in the round and then get 2 copies later and forget you've already discarded it...then become confused why you can't Ron for the triplet to win (this has happened to me and I had no idea why until re-reading the rules and looking at all my discards).

Second, if you can win with Ron and decide not to, you cannot declare Ron until the next full turn (this has ALSO happened to me). In my case I had 1-2-3-4-5-6-7-8 in dots and wanted a 9 for a full straight, but someone discarded a 6 of dots. That would have given me a winning hand but was worth less points so I passed (I was losing and needed as many points as possible). The next player then discarded a 9 of dots, but I couldn't Ron for the win because it hadn't been a full turn yet (very frustrating).