@darrenldl and @bcc32, thanks to both your suggestion I’m now able to get the completion fine
I added the PKG core to .merlin and then when I do the open Core, it gives the correct completion
But, this seems to be temporary
However, I also saw the config in .merlin keeps getting translated into
EXCLUDE_QUERY_DIR
B /Users/eklavya/.opam/default/lib/base
B /Users/eklavya/.opam/default/lib/base/caml
B /Users/eklavya/.opam/default/lib/base/shadow_stdlib
B /Users/eklavya/.opam/default/lib/sexplib0
B /Users/eklavya/.opam/default/lib/stdio
B _build/default/.sum.eobjs/byte
S /Users/eklavya/.opam/default/lib/base
S /Users/eklavya/.opam/default/lib/base/caml
S /Users/eklavya/.opam/default/lib/base/shadow_stdlib
S /Users/eklavya/.opam/default/lib/sexplib0
S /Users/eklavya/.opam/default/lib/stdio
S .
FLG -w @a-4-29-40-41-42-44-45-48-58-59-60-40 -strict-sequence -strict-formats -short-paths -keep-locs