The commands that should be added to /etc/bash_profile to change the language of messages from an internationalised program to Portuguese (pt) are:
* export LANG="pt"
* export LC_MESSAGES="pt"
The LANG and LC_MESSAGES environment variables are used to control the language of messages from an internationalised program. The LANG variable sets the default locale for all categories, such as collation, currency, date and time formats, etc. The LC_MESSAGES variable sets the locale for the language of messages, overriding the LANG variable for this category. Therefore, to change the language of messages to Portuguese, both variables should be set to "pt" in /etc/bash_profile, which is a script that is executed when a user logs in. This will affect the current user and any subsequent login sessions.
References:
* Locale Environment Variables in Linux - Baeldung on Linux
* Environment Variables - The Open Group
* [LPI Linux Essentials - 1.4 Localization and Internationalization]

The command that will correct the problem of the time being set backward by one day on a dual boot system is hwclock --systohc --localtime. This command will set the hardware clock (RTC) to the current system time and use the local time standard instead of UTC12. This will prevent the time inconsistency issue that occurs when dual booting Linux and Windows, as Windows assumes that the hardware clock is using local time while Linux assumes that it is using UTC34. By using the same time standard for both operating systems, the time will be displayed correctly on both Linux and Windows.
The other commands are either invalid or ineffective for solving the problem. The date -d '+ 1 day' command will display the date and time one day ahead of the current system time, but it will not change the system time or the hardware clock5. The ntpdate pool.ntp.org command will synchronize the system time with an NTP server, but it will not affect the hardware clock or thetime standard6. The time hwclock command will measure the time taken by the hwclock command, which will display the hardware clock time, but it will not change anything7.
References: 1: hwclock(8) - Linux man page 2: How to Fix Windows and Linux Showing Different Times When Dual Booting 3: Dual-Booting Linux Messed Up Windows Time? Here's How to Fix It 4: Wrong Time in Windows 10 After Dual Boot With Linux 5: date(1) - Linux man page 6: ntpdate(8) - Linux man page 7: time(1) - Linux man page