I had a quick gander at the datasheet.
"For any given ripple allowance set by customers" I think the idea is you come up with your desired maximum ripple as a fraction of average current and plug it in to get your inductor value lower bound. You don't need to know what the average current is. Plug \$ \Delta I_L \% = 0.2 \$ into the equation and you'll find values you need for 20% ripple. Obviously values outside \$ 0 < \Delta I_L \%<1 \$ will be invalid or cause some discontinuous current modes which might not work with the IC (would have to read in more detail).
The equations in the R_sense selection look like the same thing rearranged and for boost subbing \$ I_{L(AVG)} = \frac{V_{OUT}I_{OUT}}{V_{IN}} \$ which is what you would expect from \$ I_{L(AVG)} = I_{IN(AVG)} \$ and \$P_{IN} = P_{OUT} = V_{IN} I_{IN(AVG)} = V_{OUT} I_{OUT(AVG)} \$ and for buck subbing \$ I_{L(AVG)} = I_{OUT}\$ which matches my understanding of how buck and boost both work.
I guess they should add somewhere:
\$ I_{L(AVG)(BOOST)} = \frac{V_{OUT}I_{OUT(AVG)}}{V_{IN}} \$
\$ I_{L(AVG)(BUCK)} = I_{OUT(AVG)}\$
Maybe an oversight on expected knowledge.
From what's said in the datasheet, the buck inductance minimum bound appears to be for maximum inductor ripple current and the boost inductance minimum bound appears to be for
minimum inductor ripple current so I don't really get why the boost inductance lower bound equation is there because I can't really think of why you need to set a minimum bound on inductor ripple current? Looking closer at the equations identifying boost as minimum ripple might be a misstep, depending on the values input e.g. V_out close to V_in(max), ripple in the boost mode could be higher than the buck mode depending on values. Maybe should try bothering the support engineer for this IC/datasheet if you can.
Picking a larger inductance than the given lower bounding equations should just result in adequate ripple and stability at the cost of a more expensive/larger inductor. Setting a lower ripple (and larger inductor) should reduce magnetic losses. Obviously you also need to also be aware of inductor saturation/max current and other limits when picking your inductor.
Not familiar with the subharmonic oscillation condition so deffering to what Tim has said there. Edit: I'm having a read on slope compensation right now here
https://www.eetimes.com/understanding-nonlinear-slope-compensation-a-graphical-analysis-part-1/?page_number=2As other have suggested, I'd just run an LTSPICE sim anyway since they tend to be pretty good with LT ICs anyway and there should be ready made LTSPICE circuits for the IC too.