Should I cautious of these modified versions of the same app from Huawei?
We don't know if they are modified versions; and if they were, we don't if Huawei or the legitimate developers modified them. I have not seen any articles accusing Huawei of modifying apps. Even when using only Google Play Store, there may be a difference in the version of an app depending on the device. See below for Booking.com's additional information on Google Play Store
In Huawei's AppGallery Review Guidelines, the following is stated about what developers should do for their apps to be compliant and pass the review on the App content section:
4.5 Your app must not be a cracked version of another copyrighted app.
On the user privacy section, it is stated:
7. User Privacy
You must handle user data with caution and ensure your app complies with the laws and regulations of the countries or regions where your app is to be released. The following requirements must be met:
7.1 Your app must not collect, transfer, or use users' privacy data, such as location and contacts, without the user’s consent or other legal basis in applicable law.
7.2 Your app must provide anti-virus or security protection functions and privacy notices, and the privacy notices should include the following information: What user data will be collected or transferred, what such data is used for, and with whom such data is shared, and any other information as required by applicable law.
7.3 If your app transfers users' personal data, users must be informed how and where such data is going to be used.
7.4 Your app must encrypt users' personal information, such as identifiers and authentication, when collecting, storing, and transferring such information to ensure confidentiality and completeness.
7.5 During transactions using third-party payment services, your app must not record users' transaction authentication information or disclose users' personal information irrelevant to the corresponding transactions to any third-party.
7.6 If your app is used to handle financial, payment, or identity information, it must not disclose any of the user's personal data.
7.7 Your app must not use permissions or data that are irrelevant to the apps' functions.
7.8 Your app must not modify users' personal data within itself or other apps.
In App Audit FAQ, there is the following quesion:
Q11 Is security inspection the same for overseas and China apps?
The security inspection on an overseas app features high industry standard, and is therefore more stringent than domestic ones in terms of data acquisition and permission requirements.
If Huawei is modifying apps without their owners' consent, then it will be liable for infringing not just their own guidelines but more importantly other nations' laws.
You should worry about any apps unless you have seen and reviewed their codes. However, none of us has the possibility of doing that with most apps being closed source. Google might be modifying apps from other developers. We are left only with giving or not our trust due to past experience(s) using an app or what we have heard about an app, developers or companies.