I use Auria Pro with the FabFilter AUv3 bundle. For audio software of this caliber it's super cheap on the iPad. The desktop equivalent for Auria (Logic) is about $200, and the FabFilter plugins on the desktop are over $700. On the iPad for both it's less than $200 in total. So i get that compared to other iPad apps these seem expensive, but really it's a massive bargain. If you want to be serious about audio production on the iPad i'd say these are essential tools, especially for mastering. I'm not rolling in money either, so even at this much more affordable pricing than the desktop software i still had to save up!
To note, if you do end up getting the FabFilter plugins, don't buy them through Auria. Then you can only use them in Auria. Get the ones in the main app store and then you can use them in any app that supports audio units. Save up for the bundle as well as buying them individually will cost a lot more. And also just keep an eye out for a sale, as they do go for a bit cheaper. Actually right now they are less than they were.
As for using Auria with LumaFusion... Well they don't really work together exactly. What i do is record the video from my events to an app on my iPhone (you can use the camera app if you want or something like Switcher Studio if you want overlays and lower thirds), and also record the audio in Auria separately on my iPad. To get the audio from Auria into LumaFusion after mixing and mastering in Auria you have to first sync the video. Auria has a plugin add on you can buy that lest you import video. I use that to bring the video in from the camera with it's audio and line up the waveforms and trim the audio in the mastered tracks to the one from the video. After that i only import the trimmed mastered audio out (trimmed to the size of the clip you'll be editing in LumaFusion and drop the audio in to LumaFusion, then edit from there.
It's all a bit tricky, but totally doable. There's a lot to learn about both audio and video production and editing. Auria has the same kind of forum as this one you can join to learn about it and find video tutorials and ask questions http://auriaapp.com/forum/index.php
Also, if you want audio software that it a bit easier to learn but still great as an editor you might try Cubasis. It's slightly less powerful but more accessible and easier to figure out if you are new to audio.
Anyway... This all takes time to learn and save up for. But it is worth it to get the full versions. You can do some final mixing in Auria, but i wouldn't recommend mastering in it without the FabFilter plugins. The ones native to Auria just aren't great.
It's all a learning process. Spend time learning about audio and video production in general and any of these programs will get easier to use. There are tons of YouTube Channels that go over how to do this stuff. i actually don't follow a lot of them for Video work, but for understanding audio production i'd say your best bet to really start learning is Produce Like A Pro https://www.youtube.com/producelikeapro
The more you watch the more it'll make sense!