Here they are, based on the idea that it should be a smidge easier to find new bonuses than to conduct original research 
. This hasn't been playtested, and the numbers could probably do with a second pass, but I'm happy with the overall structure.
Balance-wise, I don't see a huge benefit from new s/m bonuses, as you're always capped by your MT. If you use the massive canonical list, you can probably cap out for most items/potent spells without too much trouble The main control in this system is that the GM says what bonuses are available, and so can err on the side of caution when extrapolation from the canonical examples.
Step 1: Identify potential shape and material bonuses
Roll Int + Magic Lore to identity potential shape and material bonuses an object may have. The ease factor is based on how obvious they are, e.g. it’s easier to work out that leaves could benefit Herbam than that red coral is good against demons.
You can also do this the other way, and roll to work out what shapes or materials would give a specific benefit. This is a bit harder than studying a specific shape or material, generally +3 to ease factor.
The GM determines the maximum magnitude and scope of the bonus. These will generally follow the core book patterns, e.g. bonuses to forms and techniques are smaller than those available to very narrow areas.
The magnitude and scope determine how many breakthrough points you need to make the potential bonus a real one.
Scope - Extra Breakthrough Points Needed
Minor magical focus - 1
Major magical focus - 3
A form - 5
A technique - 7
Example: You would need 9 breakthrough points to unlock the shape bonus of +4 to Herbam from leaves.
Step 2: Experiment to find out how to implement them
Experiment while creating an item or spell (with potent magic) that utilises the potential bonus. Assuming you create an effect that is a valid target for the bonus, you get breakthrough points equal to the magnitude of the effect, but you cannot gain more points than your Magic Lore from a single effect. You also increase your lab total as usual based on the shape/material bonus in question.
While your research is ongoing, you cannot reliably use the shape or material bonus, though you may recreate a previous project and gain the bonus (you gain no new breakthrough points).
Example: if you have a magic lore of 3, you can get up to 3 breakthrough points per successful experiment, assuming the effect was at least 3rd magnitude. If you have a Magic Lore of 6, you could do this in two seasons, assuming you created at least a 4th and 5th magnitude effect.
Step 3: Teach others
Once you have enough breakthrough points, you can now reliably incorporate the shape or material bonus. If you write a Magic theory tractatus or summa, or teach someone Magic theory, they also gain the ability to do so.