ToME: the Tales of Maj'Eyal

Prodigies "Blighted Summoning" add to summon creatures new spell/skill and "Your summoned creatures are gained MAGIC equal to yours" But alchemist golem not resive this bonus.

Which version are you playing in? In 1.2.3 it says "You necrtrotic minions and wild-summons get a bonus to Magic equal to yours." So it's clear, that the golem does not get a bonus.

Although I think the thought-forms also get a bonus, which is not speficied.

Pretty sure golems dont receive this because golems aren't summoned creatures. Golems are constructs that are built, they aren't temporary summons like a summoners pets or a doomed's shadows. If golems received this that would be REALLY powerful, it could effectively receive twice as many stat points (or more) than it gains by leveling up. If you focus all his points on strength (because that's how you "built" and "improved" his design) then he suddenly also has +50 points into magic because thats where yours was...might as well not even bother giving him optional stat points or stat restrictions on talents.

It's meant to make you choose, do you build a war machine thats built around pulverizing your foes, or an arcane cannon meant to blast with magic infused into him from a distance.

still, could have been noted "all summoned creatures, except for a golem, gain magic"

well again, golems aren't summoned. You dont call them from somewhere else temporarily, you construct them on the spot.

I could get behind it saying something along the lines of "All temporary summons" though

Technically, golems are summoned. Specifically, they fall in the Unliving, Unnatural, and Summoned categories. They get affected by the noble ego, etc.

well, there is the talent "invoke golem"(?) that summon it to you?
and then there is the supercharge, whiche summon him from the "dead"?
and i am not sure if golem portall counts in there... its a swap.