Problem 1:
column_priv_hash uses utf8_general_ci collation
for the key comparison. The key consists of user name,
db name and table name. Thus user with privileges on table t1
is able to perform the same operation on T1
(the similar situation with user name & db name, see acl_cache).
So collation which is used for column_priv_hash and acl_cache
should be case sensitive.
The fix:
replace system_charset_info with my_charset_utf8_bin for
column_priv_hash and acl_cache
Problem 2:
The same situation with proc_priv_hash, func_priv_hash,
the only difference is that Routine name is case insensitive.
So the fix is to use my_charset_utf8_bin for
proc_priv_hash & func_priv_hash and convert routine name into lower
case before writing the element into the hash and
before looking up the key.
Additional fix: mysql.procs_priv Routine_name field collation
is changed to utf8_general_ci.
It's necessary for REVOKE command
(to find a field by routine hash element values).
Note: 
It's safe for lower-case-table-names mode too because
db name & table name are converted into lower case
(see GRANT_NAME::GRANT_NAME).