I also observed in the last days, that it normally takes 4-5 attempts to raise artifacts from level 8 to 9 and 9 to 10. This is described as 50% chance. I can understand RNG, but this occurs with 80-90% of my artifacts. Shouldn't the chances to raise an artifact at that level be 50% (40% respectivly)? Have they changed these values?

Anyone else observed this huge amount of failures at improving artifacts at this level?

Hi! No, there were not any substantial tweaks regarding chances of successful upgrade of Artifacts. As for my experience, usually, it takes about 1-3 attempts to upgrade an Artifact from level 8 to 9 and similarly from 9 to 10. However, after level 10 the chance turns to "Low," and so it takes about 3-5 attempts, just as you described

I don't really care about the chances (use to them in Summoner's war) I however care about the total amount of silver needed to get them to 12 for low end (or beginner players)..

I would think that the chances would be different from a 3 star to a 6 star in regards of artifact progression but it isn't and that is the problem specially for new players. 

When you have starter missions that tell you to level 2 artifact to level 12 and it takes you darn near 600k to do so is ludacrest.

That's why I use 1 star commons for missions

What does using a 1-star or 3-star or anything matter? It's utterly irrelevant. The rarity or star-count on an artifact has absolutely no influence on the probability of success when leveling it.

not substatial? but there have been changes? hmm

It depends if you intend to keep the artifacts you boost. If I just need to get "two artifacts to L16" without regard to if or where they are attached, yes, I start with 1 star common artifacts.  It typically takes me about 250k silver per artifact, with most of that in the last 2-3 levels. Once I build them and get credit, I generally just sell them for zilch cuz they are useless.

Otherwise you could easily spend over 1 million to get one to L16, and often see very little change in stats.

Planning for the worst case, I try to have on hand 40 turns worth of silver to avoid running out in mid-increase.  But if you do run out I find that if you go grab more silver somehow, go right back to what you were doing without any break in continuity and it should just take a few more tries without starting over, in my experience.

i also had to spend over a million getting 2 things to 12 earlier, its never usually that ridiculous...i dunno whats going on atm. might be just in our heads

1-3 and 3-5 haha?? i should record my upgrades for you. 7-8 failed 7 times in a row earlier and 10-11 ive had more 10+ fails than i can even count. I think you are joking with us about those rates :P

I did not describe it the way you write it down. 

The 3-5 attempts are occurring by leveling from 8 to 9 and 9 to 10, not 10 and above.

Also...have there been tweaks to the chances, even if they are not substantial in your mind? Like dropping 10% of the chances?