Well, being heavily encumbered already reduces your speed, thereby limiting your possible jump distance. If a Strength check was otherwise necessary, a heavily encumbered character would also have disadvantage on the check. I don’t see a need to penalize the character in their attempt to jump any further than that. Jumping into a gale does seem like something that might merit a roll of some kind, but doesn’t seem by my reading of the RAW to fit under a Strength (Athletics) check. Here I might consider calling for a Strength saving throw - I think that might be particularly appropriate if the gale picked up mid-jump, for example. But if the gale is already blowing and the player describes an action with the goal of jumping some distance through the gale... Depending on the action I might go outside what I would consider to be RAW and call for a Strength check.
Again, being heavily encumbered affects your ability to swim by decreasing your speed, and by imposing disadvantage on Strength checks if one needs to be made, but wouldn’t, in my opinion, be cause for a check by itself. Swimming in a medium other than water (presumably a more viscous one, since the implication is that it would increase the difficulty of the swim) would I think best be modeled by treating the medium as difficult terrain. Swimming with one’s hands bound, I think I would impose disadvantage on any check made to swim, if one was necessary, but if you’re swimming in still water, I think it’s reasonable to allow that to be successful without a check, even with one’s hands bound.
Because having few hand holds is given as an example of a condition where a the DM, at their option, might call for a Strength (Athletics) check, I don’t think it would be going outside the rules to do so. Should “a surface with few hand holds” have been included in the bullet points under uses for the Athletics skill? Probably. The 5e rules are notoriously disorganized, but I don’t think that’s a counter-point to my interpretation of what the rules say.