Ah this nonsense again, please stop pretending you know what you're talking about. Neither engine is better than the other, they both excel in different areas. Unity is probably the better engine for what Graal 3D is trying to achieve although Unreal would also be a great choice.
Blueprints are amazing and make life so much easier but they're no substitute for scripting. You'd definitely struggle to create good quality games using them exclusively, especially when creating an MMO from the ground up. Some stuff just requires code. The Unity store has some great visual scripting and while not as powerful as blueprints can definitely improve workflow.
Unity is cheaper than Unreal for large companies. Unreal take a 5% cut on all revenue after $3000/month. Unity takes no cut and a professional licence costs $150 a month ($25 if revenue is less than 200k/year). Unreal might be cheaper for small games, but for large organisations Unity generally is.
I don't know what you mean exactly by "graphically more stable" but yes, Unreal is without a doubt better at delivering high-end visuals and offers a lot of tools which aid in this. Is Graal 3D going to utilize any of that? Looking at the Instagram post, probably not. For games which have fairly basic graphics, Unity is generally more efficient and offers better performance - particularly on mobile.
I very much doubt Graal, or any other professional developers are going to use free assets from other games so I don't think that would really matter.
Are you really trying to pin problems with the servers and bugs in the games code on the game engine? The engines aren't causing ****ty code or bad server architecture/infrastructure. Please do some research, you'll find very few people agree with what you're saying.
I'm not sure if you're overall familiar with making games with both engines, I've made games from both engines for close to 6 years now(Well,Unity for 4 years, Unreal for 2, close enough) It's not that it isn't possible to made good games on Unity, But it's more so the fact you'll simply encounter far more bugs on average than other engines like Cry or Unreal. Take a look at games like Pokemon Go, SCP(Unity Remake), Rust,Ect, And you'd see that more then likely they suffer more bugs than other engines, You'll even see bigger YouTubers like Markiplier,PewdiePie,Jacksepticeye,Etc all comment on how buggy the engine is, the People who literally play games for a living would and should know from experience more than anyone else.
I'm also not entirely sure what you mean by Unity being more efficient and provides more performance for Mobile, Not a single clue, Because Unreal runs in C++, Unreal has better ability to control memory management, ect. Though hardly any better either way, I never once experienced or seen any performance difference from the games I made on Unity opposed to Unreal when I imported them for Mobile for my friends, Never once. The only difference I ever seen in this aspect is the APK files often are a bit larger from unreal. But not enough to make much of a difference what's so ever. That's really the only difference I seen in mobile from the two.
Again, I'm not saying you can't make a good game from Unity, I used to make many Unity games literally all the time for fun, But you're far more in the likelihood of encountering bug issues, It has nothing to do with the people making these games being bad themselves, It's just the Unity engine is more likely to mess something up opposed to other engines, Not that this is a Unity Exclusive kind of problem, But it simply happens more on Unity then other engines. I'm surprised this is even an argument in itself in 2019.