Design loses font style link from time to time

We have a Figma file specifically for font styles, and we publish this file as font style source for all design files in the company.

Issue: in many design files, designers find font loses styles sometimes.
from this (we want this):
to this (we DO NOT want this):

Generally our designers need to spend many hours per week just to relink all the font with styles if they find any that loses the link.

We need help, like a lot of help for this.