Why do the console commands for making someone marryable or a follower only work on some characters and not all?
For instance, I've tried the marriage code with Ancano, Elenwen, and Ondolemar but marriage dialog options never appeared. (I was playing an unmarried character wearing an amulet of Mara, and I had already set the relationship level to 4) The follower codes don't work with them either. I tried removing Ondolemar from the Markarth Thalmor faction to see if it would work, but it still didn't. The marriage dialog didn't appear.
And when I try the follower option with Malborn, he never leaves the tavern to follow me, even though he gets the follower dialog.
Is there some way to make the console commands work every time, like another console command I need to type in, or is this issue something that only a mod would make possible?

Okay, two things: aliases and voice types.

Marriage dialogue is filtered by voice type. Elenwen and Ancano both have unique voices, and no marriage dialogue was recorded for them. Ondolemar does not have a unique voice, but no marriage lines were recorded for his voice type. Therefore, you cannot marry with these NPCs.

Malborn's reference is likely being controlled by an alias for "Diplomatic Immunity" and then his miscellaneous quest. These likely have higher priority than the follower alias, and it is overrided.

Is there a way to make the marriage work without the voice dialog? Just have it be silent or something?

I'd love to be able to hit ~ when someone cuts me off in traffic, select the car, type 'kill', then 'markfordelete'.

It really svcks that Bethesda didn't make marriage dialog for Ancano and Ondolemar's voices. They have the hottest voices in the game.

Not really. The dialogue is specifically filtered for the people that have the recorded voices.

Because the Console is not an Editor. You have to Edit the NPCs to make them be able to be followers and or spouses. Which would include any dialog that needs to be recorded.