Installed Keypirinha to c:\Program Files (x86)\Portable\Keypirinha\keypirinha.exe and doing basic config:
[external]
editor = "c:\Program Files (x86)\Portable\Sublime\sublime_text.exe"
editor_accepts_multifiles = yes
Thus getting Sublime opened with 4 empty tabs:

c:\Program
c:\Program Files (x86)\Portable\Keypirinha\Files
c:\Program Files (x86)\Portable\Keypirinha\(x86)\Portable\Keypirinha\portable\Profile\User\Keypirinha.ini
c:\Program Files (x86)\Portable\Keypirinha\(x86)\Portable\Keypirinha\default\App\Keypirinha.ini
Changing path to subl.exe leads to the same result.
Installed Keypirinha to
c:\Program Files (x86)\Portable\Keypirinha\keypirinha.exeand doing basic config:Thus getting Sublime opened with 4 empty tabs:

Changing path to
subl.exeleads to the same result.