I've got a few incomplete tables that aren't ready to be shared, but essentially... here's the "normal" range of tasks encountered, 10-200.
10 or less is an "easy difficulty" task. Something most people would be able to accomplish without any previous training the vast majority of the time, and where "failure" isn't likely to be extreme, but it's at least possible if you're unlucky. An example would be climbing up a ladder, making a 4 foot standing jump, hitting a ball off a t-ball stand with your bat.
25 or less is a "normal difficulty" task. This is something most people would be able to accomplish pretty consistently, given enough time or a few goes. Making a 5 foot standing jump, climbing over a 6ft chain link fence, catching something casually tossed to you specifically for you to catch, etc.
50 or less is a "hard task", one that average person's attempt has even odds of failing, or at least stumbling, but which they can make a partial success pretty easily. Someone with particular skill here will have little difficulty. Making a 6ft jump, climbing up a pipe fastened to a wall or over a 6 foot slat fence, hitting a dartboard with a thrown object from 8 feet away.
75 or less is a "very hard task", one that a normal untrained individual can be expected to fail at more often than they succeed or struggle over several turns to manage. Making a 7ft standing jump, climbing up a free hanging rope with knots, catching a long throw.
100 or less is a "skilled task". Skilled tasks are unlikely to be accomplished by someone who hasn't explicitly been trained - if they do, they manage the accomplishment through pure luck, and it's likely as not that any failure will be a bad one if they try. Even someone who knows what they are doing (a 50 point skill bonus) is as likely to fail or at least falter as they are to succeed. Making an 8ft standing jump, climbing up a free hanging rope without knots, or scoring a strike in bowling
125 or less is an "expert task". Expert tasks are unlikely to be accomplished consistently even by someone familiar with them - they may require several attempts, and the failure of someone unfamiliar with the task is likely to be severe. Even experts (a 100 point skill bonus) have a real chance of failing or at least faltering. Attempting to clear a long gap between buildings in wet and windy weather, climbing a greased pole, throwing a bulls-eye.
150 or less is a "master task". Master tasks should only be attempted by those who are very good at what they are trying to do. Even a someone who knows what they are doing is unlikely to accomplish this task through anything but sheer luck or rugged determination - they benefit mostly from minimizing the damage a failure does. Experts have even chances of succeeding or failing - even if you do everything right, success comes down to luck. Attempting a long jump from one moving vehicle to another moving at a different speed in inclement weather conditions, climbing the "inverted wall" from Ninja Warrior, hitting a bulls-eye from 30ft away.
175 or less is a "heroic task". You'll want to be an expert, committing extra effort, to have a reasonable chance of succeeding, and failure is still likely without a dose of luck. Accomplishing any task at this level makes you an official badass. Doing the above jump as a backflip, the inverted wall... greased, or hitting the bulls-eye with your eyes closed.
200 or less is considered an "impossible task" - especially since you can no longer succeed by critical hit for these, so you have to be an expert to even succeed 1 times out of 100. It can be done, with suitable commitment, and a good deal or luck, despite the name - but don't count on.
200+ tasks are considered legendary - Expect to fail often and repeatedly, to exert all your willpower and use up all your luck for even a /chance/ of success.
Not that when trying for a task, you can also calculate "partial success" - for a jump, this would be catching the edge but having a poor landing and needing to climb up. For a climbing task, this would mean a wasted turn where no progress was made. To calculate a partial success, consider the task's difficulty minus your bonus, divided by half. For a 150 point task against an expert (100 point bonus), this would be a 25. If you fail the task, but roll above this value, you have a partial success instead of an outright failure.