12.2.0.1 but not 12.1.0.2: Maximum key length exceeded on NLS_SORT functional index on 2 NVARCHAR(10

Relevant database parameters

database version       12.2.0.1 standard

nls_length_semantics   BYTE

nls_nchar_characterset AL16UTF16

nls_characterset       AL32UTF8                                              

max_string_size        STANDARD

db_block_size          8192

Reproduction

CREATE TABLE "doublecheck"  (    "unid"         RAW(16)            DEFAULT SYS_GUID() NOT NULL ENABLE,    "language_id"  RAW(16)            DEFAULT NULL NOT NULL ENABLE,    "context"      VARCHAR2(100 CHAR) DEFAULT NULL NOT NULL ENABLE,    "resource_key" VARCHAR2(100 CHAR) DEFAULT NULL NOT NULL ENABLE,    "translation"  CLOB               DEFAULT NULL,    "bespokememo"  CLOB               DEFAULT NULL,    CONSTRAINT "primarykey_doublecheck" PRIMARY KEY ("unid")  );CREATE UNIQUE INDEX "uidx_doublecheck" ON "doublecheck"  (    "language_id", NLSSORT("context", 'NLS_SORT=BINARY_AI'), NLSSORT("resource_key", 'NLS_SORT=BINARY_AI')  );

Error