Can you get banned for using a Playstation Plus trial from your primary account with other accounts?

No.

Public information about ban reasons says nothing about game sharing or using multiple trials on one device. List of ban reasons (they are mostly related to online interactions):

• Modified System Software
• Modified Hardware
• Reversal of Charges
• Share/Hijack Account
• Offensive Images or Audio
• Exploiting a Game Glitch
• Verbal/Text Abuse
• Hate Speech
• Your Personal Information
• Another Person's Personal Information
• Abuse of Grief Reporting Function
• Impersonating Another User
• Spamming
• Grooming
• Sexual Harassment
• Account Scamming
• Impersonating an SIEA Representative
• Child Protection
• Inappropriate Online ID
• Team Killing
• Cheat Codes
• Voice Communication Blocking
• Uploading Pornographic or Obscene Image
• Community Standards Abuse
• Cheating
• False Registration Information
• Fraud
• Disrupting a Game

For details visit Information on Banned Accounts and Consoles.

And from my personal experience: I have 2 PSN accounts on my PS4, all purchases and PS+ subscriptions are done on one of them, user from another is able to play all the games (at least in single player). No bans for us so far. I will update this answer is I ever get banned :)

See also this answer for details on account sharing.