The names of the new input methods are bad.  IMO, tamil-itrans and
tamil-inscript should ideally be renamed to tamil-itrans-digits and
tamil-inscript-digits, and the new input methods should be tamil-itrans
and tamil-inscript.  But I guess such a backwards incompatible change
won't fly?

>  2. For your item 2, submit a patch that fixes the docstring of the
>     relevant input methods.

About item 2: according to the docstring of `quail-define-package',
constructs of the form "\<VAR>" should be replaced by the VAR:

    DOCSTRING is the documentation string of this package.  The command
    ‘describe-input-method’ shows this string while replacing the form
    \<VAR> in the string by the value of VAR.  That value should be a
    string.  For instance, the form \<quail-translation-docstring> is
    replaced by a description about how to select a translation from a
    list of candidates.

but this is not the case, I checked the code but don't see a
substitution like this happen.  Maybe this should be fixed in
`describe-input-method' instead?

>
> Would that work for you?  Can you prepare such patches?