Which version of AdiButtonAuras are you using (enter the exact version number here)?

2.0.21 (2018-08-09)

How did you install the addon (twitch client/manually)?

Manually

If you installed manually, where did you download the addon from?

Curse

Creating a user rule for displaying the current amount of available runes on a spell always shows the maximum amount of runes at all times - six.

(Spell ID: Heart Strike)

ShowPower {206930, "Runes"}

Another question I have: Is it possible to display hints on spells with charges, based on the amount of charges left? For example, flash when maximum amount of charges is reached? There is no Aura/Buff ID to bind such a rule to.

ShowPower does not work for runes, because they are designed differently then other class power resources. You will have to right a Configure rule for that. I might add this as a standard rule though when I'm back from vacation.

Yes it is possible, look up the ShowStacks rule in the documentation.

Yes it is possible, look up the ShowStacks rule in the documentation.

I've tried that but the spell I want that rule for (Blood Boil) doesn't provide a buff aura. I've tried binding the spell to the spell, so to speak, but that didn't work out:

ShowStacks { 50842, 50842, 2, "player", 1.0, "hint"},

Another thing, that I've noticed, is that the default "good border" of buffood/items isn't displayed for some reason.

Enjoy your vacation.

For displaying ready runes on Hearth Strike create a user rule with the following body:

return Configure {
	'HearthStrikeRunes',
	L['Show the number of ready runes.'],
	206930, -- Hearth Strike
	'player',
	'RUNE_POWER_UPDATE',
	function(_, model)
		local numReady = 0
		for rune = 1, 6 do
			local _, _, isReady = GetRuneCooldown(rune)
			if isReady then
				numReady = numReady + 1
			end
		end
		model.count = numReady
	end,
}

For the charges rule (sorry I misunderstood you on this one):

return Configure {
	'BloodBoilCharges',
	L['Hint when @NAME has more than 1 charge.'],
	50842, -- Blood Boil
	'player',
	'SPELL_UPDATE_CHARGES',
	function(_, model)
		local numCharges = GetSpellCharges(50842)
		if numCharges > 1 then
			model.hint = true
		end
	end,
},

Another thing, that I've noticed, is that the default "good border" of buffood/items isn't displayed for some reason.

I'll take a look.

thank you very much.

Another thing, that I've noticed, is that the default "good border" of buffood/items isn't displayed for some reason.

The reason is that LibItemBuffs-1.0's extractor does not pick up the buffs. I'll need some time to fix this as I'm considering rewriting the extractor. I'll close the issue here. You can track AdiAddons/LibItemBuffs-1.0#4 for resolution.