We need three new namespace for ne.wikibooks. They are as follows:

'पाकपुस्तक' (Cookbook), 'बालपुस्तक' (Wikijunior) and 'विषय' (Subject)

also their respective talk parts

'पाकपुस्तक वार्ता' (Cookbook talk)
'बालपुस्तक वार्ता' (Wikijunior talk)
'विषय वार्ता' (Subject talk)

then, we need following aliases with some priority

'Wikibooks' => NS_PROJECT,
'Wikibooks talk' => NS_PROJECT_TALK,
'Cookbook' => 'पाकपुस्तक'
'Cookbook talk' => 'पाकपुस्तक वार्ता'
'Wikijunior' => 'बालपुस्तक'
'Wikijunior talk' => 'बालपुस्तक वार्ता'
'Subject' => 'विषय'
'Subject talk' => 'विषय वार्ता'

and following aliases with lesser priority

'विपु' => NS_PROJECT,
'विपु वा' => NS_PROJECT_TALK,
'प्र' => NS_USER,
'प्र वा' => NS_USER_TALK,
'ढाँ' => NS_TEMPLATE,
'ढाँ वा' => NS_TEMPLATE_TALK,
'श्रे' => NS_CATEGORY,
'श्रे वा' => NS_CATEGORY_TALK,

Community Discussion link:https://ne.wikibooks.org/wiki/%E0%A4%B5%E0%A4%BF%E0%A4%95%E0%A4%BF%E0%A4%AA%E0%A5%81%E0%A4%B8%E0%A5%8D%E0%A4%A4%E0%A4%95:%E0%A4%9A%E0%A5%8C%E0%A4%A4%E0%A4%BE%E0%A4%B0%E0%A5%80#New_namespaces_and_aliases_for_ne.wikibooks

Regards
Biplab Anand
(U:बिप्लब आनन्द)