National Electronic Injury Surveillance System (NEISS) is a great resource for free-text details of emergency-room visits, including fatalities.
Unfortunately (for you), years 2009-2015 show cutting-based coconut-related injuries (plus one allergy):
46 YOF WAS CUT W/KNIFE WHILE CUTTING A COCONUT. DX: FINGER LAC W/DIGITAL NERVE INJURY.
31YOM CUTTING A COCONUT WITH A KNIFE AND SUSTAINED A FINGER LACERATION
53YOM WAS CUTTING COCONUT AND LAC FINGER WITH KNIFE
72YM FOR AF, WAS CUTTING THE BOTTOM OF COCONUT TO MAKE BIRDHOUSE
WHEN IT SPUN RUNNING HIS HAND ON THE TOP OF THE TABLESAW>>LAC
34YOM CUT LEFT FINGER WITH A KNIFE WHILE CUTTING A COCONUT, LACERATION OF LEFT THUMB
24 YOM WAS TRYING TO CUT A COCONUT WITH A KNIFE AND CUT HIS HAND. DX HAND LAC
13 YO MALE SLICING A COCONUT AND CUT FINGER WITH A KNIFE. DX LACERATION FINGER
9 YOF STABBED HAND W/A KNIFE WHILE OPENING A COCONUT. DX: R HAND LAC .5 CM.
9YO M OPENING A COCONUT WITH A SHARP BLADE AND POKED FINGER DX PUNCTUR E WOUND TO FINGER
46 YO M, C/O CUT TO LT HAND, WAS TRYING TO OPEN A COCONUT W/ A KNIFE WH EN HE ACCIDENTALLY CUT HIMSELF, DX HAND LACERATION
27YOF W/ALLERGY TO COCONUT, MOTHER USED COCONUT ROOM DEODORIZER PT. HAD SOB AND CHEST PAIN.
43 YOF, PT WAS USING KNIFE TO CUT A COCONUT, KNIFE SLIPPED & STABBED L T HAND. DX; LAC LT HAND
CUT WITH KNIFE WHILE CUTTING COCONUT. 35 YO F LACERATION L HAND #
36 YOM WAS CUT W/KNIFE WHILE PEELING COCONUT. DX: L HAND LAC 3 CM.
41YOF DRILLING A HOLE IN A COCONUT AND BIT R AND PUNCTURE HAND
PT CUTTING A COCONUT WITH A KNIFE AND SUSTAINED A LACERATION TO FINGER
PT WAS CUT W/KNIFE WHILE CUTTING COCONUT. DX: R HAND LAC.
PT TRYING TO OPEN A COCONUT WITH A HAMMER STRUCK SELF IN THE HEAD WITH THE HAMMER CLOSED HEAD INJURY
DX LAC REPAIR/TETANUS BOOSTER: LAC TO PALM OF L HAND W PAR'G KNIFE W CUT'G ON COCONUT THIS EVEN'G
PT CUT FINGER WITH A KNIFE WHILE CUTTING OPEN A COCONUT AT HOME TODAY DX// LEFT INDEX FINGER LAC
So, probably there are very few recorded falling-coconut accidents, and, similar to shark attacks, most would be then cataloged on Wikipedia.
By the way, you can download individual years as XLSX, or you can export year-by-year by search the Query Tool without any parameters, and then exporting CSV, or this data has been exported to R-stats.