While theorizing a build, I realized a couple of things.
1) Ranger has greater spell focus as a bonus feat but not normal spell focus
2) Ranger does not have EDR as a bonus epic feat.
While the second one is debatable in if it would be fitting, the former one seems rather contrived. The fact that if one gets a spell focus they can use a pre-epic bonus ranger feat for a greater spell focus, but cannot use it for a normal spell focus makes it incredibly awkward and seems like it would not be unjust to allow normal spell foci be an option. In the case of casters dipping ranger, often they do so anyways to use it for a bonus epic spell foci, which while basegame behavior becomes even more baffling as rangers cannot take such themselves.
In the case of the second? The ranger epic feat list is somewhat limited. With the introduction of bloodlust, people liked the idea of a lifesteal EDR tank. While building such is rough at the best of times given the stat spread, given too the lack of DI and innate DR ranger has it does not seem like it would be insanely strong, and likewise would be fitting and so too help given that EDR is 3 whole epic feats when you only receive 4 epic feats by default normally. Allowing EDR as a ranger bonus feat does not seem like it would be too crazy and would help people wanting to build EDR ranger (lest we get crazy ideas of making EDR 3 be only 2 feats that give the same value to help things like DD with its 0 bonus feats)
Edit: at the behest of another, they ask I give consideration too for brew potion. Specifically brew potion if not any of the three crafting feats, in part to synergize well with herbalism and their kit