The Goblindbergh/Black Garden/Kaiser Colosseum scenario I asked about earlier had me confused...all the answers I got here and on NAC were the same, but everything I've had pounded into my head about SEGOC over the years spoke differently (which was my main concern; G'bergh = optional, Garden = mandatory).
Finally decided to do what, in hindsight, should have been the first thing I did: check the rulebook.
http://www.yugioh-card.com/en/rulebook/SDCR_Rulebook_EN.pdf page 44
If effects of Spell Speed 1 cards (like Trigger effects) are activated at the
same time, they will be resolved in a special Chain.
This Chain is made starting with the turn player’s effects. If there is
only 1 effect, that will be Chain Link 1.
If there are 2 or more effects, the
turn player builds the Chain with their card effects, selecting the order
in which they go on the Chain. Then the opponent continues the Chain
with their effects. Therefore, the effects will be resolved starting with
those of the opponent.
So apparently Konami's made it to where SEGOC is "Turn player's effects, then opponent's effects, mandatory/optional status be damned," which means I can make G'bergh CL1 and Garden CL2.
So that's something learned...still, thanks for the help Alter.