These days, I have difficulty actually filling the 15 bodies in Ariadna with how the faction's foundation is structured. It's not exactly a cost-efficient faction anymore. Even if the cap got increased (which it shouldn't), the problems wouldn't be fixed.
Me, personally, playing CHA in 8+8 or 9+8 format, never used more than 5 camo markers, and still felt strong against most of the N3 armies. Yes, Wallace converts irregular in regular, but thats especifically his work and designed to do that, with the drawback of being the OBVIOUS Lt. That's why he was never allowed to be Lt in Vanilla. Regarding hordes, yes, all faction can play hordes, trying to mimic Ariadna style, but our hordes are usefull and efficient, many figures in the list could be especialist or bring useful tools to the battle. Other faction hordes are like you said, hollow orders to fuel the heaviest rambo they could fit in the lists. Same same, but different.
I don’t think being able to take one or two troops more would change much for Ariadna. But I do think they need a few other things to be a bit more competitive. While this might not be correct, I always thought of them being the better PH faction. PanO had BS, YJ had CC, Haqq had WIP. The Line Kazak had PH11 while the other factions PH10. This could be something they could lean into bit more in some way. Dodge +3 for example. +1 to medic rolls? Also, more PS -1 or more on more CC weapons. I can understand not wanting Ariadna getting super techy like the others but there are different things they can do to get around camo/mimetisim. Triangulated fire is one. They currently have no one with it. It’s a skill that’s not on many SWC weapons. The only one I can think of is Major Lunah and recently the Fenics got it on a Thunderbolt but it’s no SWC. Sensor can also be a “poor-mans” MSV. You get a better chance to discover but after that it doesn’t help with the mimetisim. Right now, they only have it with Antipodes. It would be good if they had another troop with it. As mentioned, Tac Aware would go a long way. They don’t need to put it on many troops. Just some elite and vet troops. Vet Kazak, Minutemen and Moblots for example.
Lets get this stright. The "N3 CHA list with over two full combat groups" has allways been a meme and has never won a serious tournament. Somebody played it in the interplanetario and it didn't perform well. I was in quite some tournaments during N3 and the factions that won the most were factions with less models like aleph, tohaa and to some extend combined army. I have the 2019 stats, those are still posted in this forum and that super crazy CHA performance is a simple 51,22% winrate, the highest result of the ariadna factions. A solid performance but definitely not game breaking. Additionally the average model per list for cha was 16. 18 for the top 33% players, definitely not 20+. Now that this is out of the way. Nobody is asking to have the possibility to field 3 combat groups again, not even 20 models. 16 models was great because it allowed 10 model lists, 10/2, 10/5, 8/8 and everything in between, with that N3 was quite varied outside of the most competitive lists. For ariadna it was way more varied than N4 with the bear list. Back then usarf played totally different compared to cha or CA, aleph, nomads etc. Nowadays everyone plays 15 and it's extremely boring. The loss of gameplay variety and faction identity is incredible. Increasing the cap to 16 and making it way harder to reach for elite factions while adjusting profiles to keep everything balanced would be very beneficial for the game. Would that fix ariadna? Probably not but it would help a lot to have a way better game. I want to add something regarding hordes. Most people use that word like some sort of brainless exploit tactic, when in fact it was not the case for usarf. People who played that faction knows that it didn't had a big scary model to carry the list like the unknown ranger was during N4. With usarf you had three separate dudes with some mines a flamethrower and a hmg to emulate what other factions could do with one single model. You had to combine your troops for everything and every single troop except UR and Minutmen had a important role in the faction. And you know what? It was GREAT, and it created quality gameplay full of interaction. It was by no means competitive but it worked and it was fun.