Realizing I only have a very general idea about the CPC’s intervention (?) in Tibet. They don’t have to be pro-Communist sources if the brainworms are mostly under control.
Melvyn Goldstein is one of the most famous Tibetan anthropologists. in the 90s, there was a ton of atrocity propaganda about forced sterilizations in Tibet, almost exactly like what’s currently being alleged in Xinjiang. Goldstein’s research essentially disproved it, and now even Tibetan exile organizations largely accept the reality.
https://sci-hub.se/10.2307/3182072
https://savetibet.org/new-report-disputes-charges-of-forced-family-planning-in-tibet/
especially nice is on page 24, they describe how women in Tibet have essentially the same fertility rate as indigenous Tibetan communities in Nepal.
When Serfs Stood Up In Tibet by Anna Louise Strong, 1959
the CPC’s intervention (?) in Tibet
I think the sources you look at will cover this better than I can, but Tibet joined the PRC in 1951. When conflict arose in '59, it was driven by the Tibetan leadership seeking to secede. Except when looking up the annexation itself, I have never seen the simple fact of Tibet’s status acknowledged in atrocity propaganda about '59.