The beacon of hope affects all healings, including healing potions
the glow of hope spell states:
For the duration, each target […] recovers the maximum number of possible points of life of any cure.
And healing potion States:
You regain life points when you drink this potion …
So drink a healing potion would count as healing and so he would be affected by the glow of hope to spell.
Your calculations are correct, a common healing potion would heal 10, a greatest healing potion would heal 20, a superior healing potion 40 and one supreme healing potion 60.
If they had wanted the feature to work differently, they would use different phrases in the same way as with Life Cleric's ultimate healing function:
From the 17th level, when you will normally roll one or more dice to restore health with a spell, you use rather the highest number possible for each de …
This feature limits maximum healing to spells, but glow of hope does not have such a restriction.