Can you get freckles in animal crossing welcome amiibo

You can fix it by manually replanting the flowers, and plucking the weeds.

You can't really undo it at this point. The game recognized you as being away for a year, and your town progressed accordingly. There aren't any special mechanics relating to time travel beyond the normal passage of time going forward, time traveling to the future just accelerates things. Likewise, going back in time won't undo changes to the town (because you can't travel to the past in normal gameplay) -- so game data (the town) is manipulated and saved relative to the player's timeline as time passes.

If you wish to time travel again in the future, you can prevent changes to the environment by enacting the Beautiful Town Ordinance, which will keep your town in a persistent state (for the most part) while you're away. Villagers will still notice your absence, and your mail will still back up... but it shouldn't cause too much damage otherwise.

And for a bit of trivia... some of the other entries in the series did actually have penalties for time traveling, but they have been relaxed in New Leaf.

No, you cannot swim to the Island in Animal Crossing: New Leaf. The only way to get to the Island is by booking a ride with Kapp'n for 1,000 Bells. The exact requirements for unlocking the Island can be found here. They are:

1. Get your house built.
2. Pay off your mortgage.
3. Wait a day for Tortimer to show up and give you the invite to the island.
4. The day after that you can go to the island.