HSN WISE summary in GSTR 9 COLUMN 17 AND 18

We are also facing same problem.  4 digit HSN are not available there in GSTR-9.

So far as the GST Rate under one 8 digit HSN vs the other does not differ you can still put the same under one head and declare. In case you face any query later, you may be able to support the same with the actual descripttion in the Sales Register. As far as there is no tax rate change the revenue shall not query or cross check the same  

Try and fill the details directly @ GST portal - 4 digit details are accepted auto search option is on when you type 2 digits

No 4 digit HSN not available instead list of all eight digit HSN, starting with your punched 4-digit, appear for selection. I also tried offline utility where 4-digit HSN sheet successfully validated but JSON so generated shows 'schema validation faliure' while you try to upload.

Then work out as per earlier reply. Govt. has clarified vide press release dated 03.07.2019, that such declaration in GSTR9 is for information purpose only and no adverse findings or proceedings shall be intiated basis mis-declaration under the said annexure.