So hammer of light was a bug or intended?

you are absolutely right and I will not use it.

yea the tree should have been designed for multiuse from the beginning since the tooltip didn’t change since march.

and no you can not interpret it as both. because non of the tooltip states that this is supposed to happen:

and i don’t see that the tree is clearly designed around one time use.
There is only the talent “hammerfall” that hints towards the single use but only if you expect hammerfall to be used inside burst window - and all other talents fit the multi usage. And even hammerfall is still valuable in multiusage because shake of the heavens will be refreshed with every use of HoL so you will have more emyrian hammers triggered by Hammerfall outside of the burst window.
→ I don’t see any reason why this design does not suite HoL multicast
on top of that it seems like the general consensus it that templar is underperforming compared to herald. So something did not go well on this tuning in combination with single usage.

I think you forgot about all the haste% loss that you have due to the gear / level 80scaling that will make the spec feel more clunky by default. There will be much more haste to get till you are at max item level so that building up 5hp shouldn’t be a problem.
I already argued that building up 5hp is no problem already now.
I don’t think its a problem to press 2-4 gcds on builders as long as you have builders to press. And with the new higher proc chances on the auto attack resets that shouldn’t be a big of a problem and it will further improve with the better gear.