list->hash-table:

Why is sizehint missing?
Should not list->hash-table accept all arguments listed
at make-hash-table?
Another approach would be to allow list->hash-table
to work only on an existing hash table.
(But then the name should probably be changed.)

There is a short discussion whether the list elements
are (key . val) or (key val).
Given this and your choice (key . val),
I would propose to change the name to something like:
alist->hash-table

hash-table->list:

rename to hash-table->alist (see above)

hash-table->vector, vector->hash-table:
Should these functions be added to this SRFI?

Just to be sure this overview of "pre-SRFI-69 implementations" is mentioned once:
www.shiro.dreamhost.com/scheme/wiliki/schemexref.cgi?Concept%3aHashTable

Greetings
Sven