I have found the solution but I cannot do.

@Arsalan Shah, is it possible for this component to be fixed or not? or fixing will require a change in the core file itself.

To fix this component, we need to make 2 variables/locale print names:

•username (exisiting)
For registration

•useremail (to be made)
For login pages

What we need is to seperate the email address from the username (email added as a check in username is the current content of the login.php file)

Announcement:
This component has been declared "recalled" and "abandoned" by me. But, if the problems of this component were fixed I am ready to get this component re-released.

Which of these:
•$username =
•input('username');
•$login->username

None of them

Recommendations: Do not use this component unless the issue has been fixed.

Which of the following is the print name for the locale file that I should change so that it will change in the locale file.
If you can please identify the function name in PHP.

Which of these:
•$username =
•input('username');
•$login->username

I am still studying the OSSN locale file structure. But basically the fix here is simple, but can't explain.
But here's an analogy:

I want the username print name to become usernamemail
Then it will apply to the login pages and locale.
While the register.php will use the username print name.

What I need is to just change the print name. Please help me because I cannot do it right now.

Files to change the print name username to usernamemail:
https://github.com/thedoggybrad/StrictEmailLogin/blob/master/actions/user/login.php
https://github.com/thedoggybrad/StrictEmailLogin/blob/master/actions/admin/login.php

Print name is different from the function name
Basically the print name is like com.ossn:speedtest

Version 1.1 (Emergency Fix):
This fixes the issue regarding the 3 Email Address fields on Sign-up.
This is just a band-aid fix that changes the locale file variable to "Email (Login) or Username (Registration)".
A real fix will require modification of the OSSN Core which I do not recommend and I have never tried either to do so.

If you want to help fix the problem entirely, please let me know here or at my email address.

Issue (not certainly a bug):
In the sign up field there is a 3 email address. The 2 are real email address and the other one is the username. I will look and fix it in version 1.1 as soon as possible.