Hello Cubecraft, i suggest updating the 1.9 server to 1.12 for the following reasons:
-The versions people uses most are 1.8.9 the latest version and sometimes 1.12
-Pvp clients only update 1.8, 1.12, 1.15 and 1.16
-Almost no one uses 1.9, 1.10 and 1.11
Tip: Try to implement it when that spring adventure is over so no need to update spring adventure
P.S 1.8 won't be affected
-The versions people uses most are 1.8.9 the latest version and sometimes 1.12
-Pvp clients only update 1.8, 1.12, 1.15 and 1.16
-Almost no one uses 1.9, 1.10 and 1.11
Tip: Try to implement it when that spring adventure is over so no need to update spring adventure
P.S 1.8 won't be affected