When modifying motion[x,y,z] of spawned projectiles as such:
 

execute as @s store result entity @s Motion[0] double 0.0002 run data get entity @s Motion[0] 10000
execute as @s store result entity @s Motion[1] double 0.0002 run data get entity @s Motion[1] 10000
execute as @s store result entity @s Motion[2] double 0.0002 run data get entity @s Motion[2] 10000

Arrow and trident visually follow incorrect path and positions correctly updated on collision with block or entity. all other functions/commands/collisions run in correct path, as shown by particles emitted by arrow in video attached.

occurs both on tick entity is generated and ticks afterwards.