My samples make use of flipped tiles. For example, the tileset only contains one corner tile, but if you mirror it horizontally and/or vertically, it works for all 4 corners.
The animation is a 4-frame loop and runs vertically on the sheet for all the water tiles.
If you need more help, i encourage you to join the Mana Seed Discord server. I or someone else can provide you more hands-on assistance.