Schools should be respecting the inherent right of everyone to express themselves as they see fit, as long as that isn't harmful to others, by coercion children through threats of punishment by not calling a teacher by their preferred pronoun goes against their own policies and Section 406 of the UK's Education Act 1996 prohibits the promotion of partisan political views in schools and requires a balanced presentation of opposing views.
The discussion surrounding "gender ideology" relates to the argument that promoting certain ideas about gender identity in schools constitutes political indoctrination, and is therefore prohibited under this section of the Act making it illegal for schools to force children to use transgender pronouns against their will.
That’s why boundaries are important, the core issue mainly is that it will involve a potential conflict between a teacher's right to express their protected belief in gender identity theory and the rights of children, their parents and colleagues who may hold different views.
The legal aspects of this are complex hence why recently schools were instructed not to teach about "gender identity" as a factual concept under new government guidance for relationships, sex, and health education (RSHE).
Bridgett Phillipson Secretary of Education has made her position clear on the matter and clarified that teachers can ask to be called "Mx" but cannot insist on it, meaning students or staff should not be sanctioned for refusing to use the transgender teachers preferred pronouns.
If children are being punished, or being threatened to be punished because they choose to or mistakenly use the wrong pronouns, then this is seen as gender ideology, which goes again the Government stance on the matter and the school could face legal ramifications.
If your children have encountered punishment, it is advisable to consult the school's official policies and, if necessary, seek clarification from the relevant education authorities, such as the Department for Education in England.