Tanking Stances 5% accuracy boost isn't added to Accuracy in the Character menu.

[Kaneki]

Increases chance to hit by 5% is pretty much accuracy. Also it's a stance unlike internal release which is a buff. It matters more to see increased stats in a stance than a 15-30 second buff with a cooldown. The reason why I think the extra accuracy from the stances should be added to the accuracy stat is so that tanks can optimize gear easily. It's not to hard to use a calculator but it really shouldn't be necessary because the stat increase should be visible. There's no reason for it not to be, bug or not.

[Daeriion_Aeradiir]

Increases chance to hit by 5% is pretty much accuracy.

Not necessarily. I'm unsure of the game's accuracy formula, but 5% hit rate may easily be stronger or weaker than 5% accuracy, depending on how they do hit rate calculations.

For example, say in a game your hit rate is your (accuracy divided by your opponent's evasion) * 100. So if you had 500 accuracy and your opponent had 1000 evasion, your accuracy would be 50%.

(500/1000)*100 = 50%

If you got 5% more accuracy from a skill, you would now have 525 accuracy, or a 52.5% chance to hit.

If it was +5% to your hit rate however, you'd have a 55% chance to hit instead.
((500/1000)*100) + 5

It all comes down to how FFXIV handles hit rate calculations, but hit rate +5% =/= +5% accuracy in all situations and hence why it's not displayed to the player. If you know the formula and the accuracy caps of whatever floor/turn/etc you're in, you'll still be able to optimize, but changing it to +5% accuracy might in fact be harming your chance to hit, or benefitting it.

[Kaneki]

The way I've been thinking about it is: Let's say i got 600 accuracy when I go into defiance I should get + 30 since (600*0.05) = 30. (600*1.05) = 630. But you never know.. I wish they made it clear..