So, the Bo-Katan event now requires R8? Or R9? Or R whatever? Nobody knows!

What zones, what battles, dont just say R9s getting spanked.  I have not changed any teams and are you on about kessel or further?  Lack of detail is annoying, be specific.

TB has not changed at all for me and the issue that someone states well i cant do BKM because its bugged and i just did it with a few changes of mods for each tier but told im a liar lol.  Up to you, moan or try, its your game but BKM can be done on r7 toons.  Its annoying, yes.

Technically you can see it this way because that is what it in fact is.
There is a requirement to access the event. What you need to be able to complete it will vary based on a number of factors, including your skill or lack thereof, and is thus not a fixed point. It isn't a secret, it doesn't exist. They could publish a recommended level, but then you would cry because you still couldn't do it.
I didn't mention a difference, there is no difference. The requirements for the event have not changed.

Even TB is impacted by Relic delta and it's not working right.  My R9 characters are getting spanked by R5 characters and that wasn't the case before delta was implemented.  It's doing things it shouldn't and causing trouble where it shouldn't.  

CG should have ensured this worked 100% and correctly before pushing it to the game.  I'm losing matches now I haven't lost in a year and my relic levels have improved.

Technically, you could see it this way. Then you'd have two requirements, one for access and one for passing the event. But why are we only being told about the first one? That doesn't make any sense. No one just wants to participate in an event, they also want to complete it. So in this case, the second requirement is the much more important one.

What's more, the difference you mentioned didn't exist before the anniversary update! R7 was the required access level and also the level you needed to complete the event. So they changed it without telling us. Why? Is it a secret? Or do they think it's more fun for us to figure it out for ourselves?

If they're going to make such important changes in the game, they might as well just tell us about them – it's not too much to ask.

The requirements aren't an indication of what you need to complete the event, they could never account for imbeciles, they are the price of admission.

I’ve been retrying the same tier 1 since I wrote that post, and still haven’t been able to get past it, other folks in my guild have been experiencing the same issue.

Sorry, but it did! EA already confirmed that, just read through the former post:

https://forums.ea.com/idea/swgoh-bug-reports-en/units-changed-in-journey-guide/12971613

I tried tier 1 at least 20 times with a R7 Kelleran Beq (295 speed, 147k protection, both zetas) and came not even close to winning. Other players had the same problem, as you can see.

So it's not a question of modding or gameplay. Before the update, several of my guildmates managed to do it with worse stats. 

And you can't actually do much else than first attacking the veteran and afterwards the clone captain - that's how it's supposed to work.

It doesnt, i just did it with r7 ig11 and r7 bando.  Trick is to put defence and health mods on bando to survive (around 60-70% defence at least).  Timing damage immunity along with phase 1 and 3 special is crucial.