did you do it one more time after it was full because even though you filled it up that 5th one is still counted as number 4 so its not 100% but now that you have 5/5 next one should be the next level.
Seems like a really unfriendly and unpredictable black box situation, and a sucker's bet, where you can spend millions with no idea of the likelihood it will really help, and with no way (like luck stones) to affect the outcome. It says there's "a chance" of an upgrade, but doesn't reveal if its .0001% of a chance, or 1% or 10% or whatever.
When i had lvl 5 enlightenment on my Templars, I was dreading the 70 enlightenments necessary to reach lvl 6. But I was lucky enough that around my 10th enlightenment, it upgraded to lvl 6.
Lvl 7 enlightenment requires 110 upgrades, though. So 110 million daru.... Might take a while.
In response to the person who asked if he should continue even though he keeps getting Matk enlights, the answer is "yes!"
There are quite a few different enlightenments. Patk/ Matk/ Pdef/ Mdef/ HP. I think that's it. When you attempt to enlighten your troops, you will get one of these bonuses which are randomly generated. If you get an enlightenment you don't like, then keep enlightening. If you can't afford to do at least 5 enlights in a row, you probably shouldn't bother. But really, it comes down to personal preference.
Also mate, I don't know if you noticed (I didn't notice 'till someone pointed it out to me) but HP gives a higher % bonus than the Patk/ Pdef/ Matk/ Mdef
Lvl 5 HP bonus is 25% of troops HP. Lvl 6 HP bonus is 45% of troops HP. Can't remember the earlier lvls, and don't know the later ones. Yet
I'm going to assume you are looking at the % bonus for Templars so I will tell you those are typos. You are correct that HP enlightenment gives a higher % bonus but it DOES NOT give the listed %. If you want to know the actual increase you need to look at HP enlightenment for Knights and other lower level troops.