hi fabilabo, translucent materials use reflection captures in different way than regular opaque materials i had the same problem basically the closest capture to object pivot is used. if you need your ocean object to move and use multiple captures there is no way to smoothly interpolate between them. You might want to use cube map to get single good reflection source for that set specularity of your shader and use emmisive to fake reflection. you can affect reflection of certain water region by lerp-ing multiple cube maps inside shader.
and here is my translucent water you can take look at
