Sorry for the delay! @chat box, no, the Eternal forums do not have the tack plan locations - the LC ones do, but we've got them up here now!
Here goes. ( C ) - construction plan, ( S ) - sewing pattern.
( S ) Embroidery Thread - MissGavel's Academy, Angled, L2, 8CP

( C ) Blue Embroidered Bridle - OrchardSan Family Cabin, Curvy, L5, 50CP
( S ) Blue Embroidered Pad - Angled Forest Isle North Shack, L5, 40CP
( C ) Blue Embroidered Saddle - Puzzle Family Home, Angled, L5, 300CP

( C ) Green Embroidered Bridle - LadyTreasure's Hut, Vine, L5, 50CP
( S ) Green Embroidered Pad - Decay Haunted House, L5, 40CP
( C ) Green Embroidered Saddle - Brown Isle Seaside Shanty, L5, 300CP

( C ) Purple Embroidered Bridle - Square Isle Abandoned Shanty, L5, 50CP
( S ) Purple Embroidered Pad - Steel Family Home, Barren, L5, 40CP
( C ) Purple Embroidered Saddle - Glacier Auction House, L5, 300CP

( C ) Pink Embroidered Bridle - Sprout Isle Seaside Shack, L5, 50CP
( S ) Pink Embroidered Pad - DrearySmurl's Mushroom, Seedling, L5, 40CP
( C ) Pink Embroidered Saddle - PreenAndPrimpSmurl's Home, Petal, L5, 300CP

( C ) Red Embroidered Bridle - Line Isle, SouthWest House, L5, 50CP
( S ) Red Embroidered Pad - Boot Isle, Rickety Barn, L5, 40CP
( C ) Red Embroidered Saddle - Drop Isle Seaside Shack, L5, 300CP