Gavilar, in particular, was an interesting case because he completely messed up and failed despite, yes, having been chosen as a recepient of the visions and even possessing characteristics that should have allowed him to become a Bondsmith. But he took a complete left turn. Elhokar, I didn't like that he was succeeding, as his character didn't evolve _that_ much, and we saw no hint of artistic inclinations from him. OTOH, it has been established that cryptics sometimes bond wrong people, like that one warrior, who was unable to progress.
But as to people striving to come together - those characters need some fleshing out for us to care. Opportunities for which are rather limited with the 3 main PoVs hogging the lion's share of the text. _And_ it has been stated that proximity to a Radiant makes it much more likely that a person will be looked at, and, if compatible, bonded by a nahel spren. Hence also the squireship system that serves to properly attune a person to the Ideals and to bring them to the attention of the spren.
Waking up of the Sibling to unlock full capacity of Urithiru has been foreshadowed as an important plot arc for the next 2 books. The character who is going to do that should have already been introduced and somewhat established. So, who?
But does he actually want that? Because if so, OB was a spectacular missed opportunity, with both Adolin and Elhokar positioned to be involved and also being people whose world was turned upside down the most by the emergence of the Radiants.
I do agree with you that people who are currently in other Orders may become Bondsmiths. In fact, it wouldn't surprise me if that is how it mostly happened before the Recreance, because Bondsmiths require a certain level of life experience to be able to guide effectively and at the same time are too unique to have squires. Which would have led to all the best candidates in Urithiru being snapped by other Orders long before they attained the necessary qualifications for becoming a Bondsmith or a position became vacant.
OTOH, I really don't see Jasnah as one. Frankly, she already has too much on her plate as queen-in-exile and the only currently existing Elsecaller. She needs to be exploring Shadesmar and talking some sense into the Nahel spren, as well as figuring out new ways to deal with a Desolation and counter-act the Everstorm, not ruling a displaced nation or running Urithiru. There is nobody else who can do what she needs to do as an Elsecaller and a brilliant thinker in order to give anti-Odium alliance a chance.