It looks to me like full automation of wood production is only possible when using only a selected set of seed types as otherwise it is not possible to reliably filter out the overproduced seeds from an Arborium / Mulcher loop.
Reducing the average seed production to one per sappling would make full automation using any mix of seeds possible.

with the 0.16 filter splitter, just filter out wood, the rest will always be seeds. I usually put the overflow in boilers.

yes, filtering 1 item type (raw wood) instead of all the seed types gives the same result but with much less effort :-)
it's also possible to change the amount of wood and seeds in the mod settings to get the desired average of only 1 seed each.

but there have to be some changes now in 0.17 since wood no longer exists in 0.17 and what is called wood now is the old raw wood.

btw: just before 0.17 released, i made a setup (using default mod settings) with a central warehouse, 6 arboriums and 2 mulchers, and lots(!) of combinators, that kept producing the least available items (seeds and/or saplings), slowly increasing the limit so that in the end i would have the same number of 1k+ of every item so that i can plant a full chunk (1024) of trees of the same type at once, and relatively quickly produce another 1k of trees of that same type from the 1k of corresponsing seeds i had in storage :-)
all that was powered by a self-sufficient wood production (with KS burner generators) that had maybe up to 500+ wood per minute surplus to use elsewhere, eg at a normal powerplant (500x8x50%=2GJ/min or up to 30+MW !?). ideally suited for self-sufficient outposts, still giving half of that power even in a desert without water (using KS generators again)