Even that reference does not say anything close to "During Stalin, it was the general policy to suppress national languages." There was no such general policy, the thing you link talks about the tension between the desire for centralized (typically Russian) control and the Marxist ideological demands of 'internationalism'.

There was no "tension". Formal internationalism was quite effectively replaced with persecution of ethnic and religious minorities, including suppression of languages and education. Internationalists were some groups like Makhno's anarchists. Stalin was the complete opposite.

But I think I'm wasting my time here. If you want to deny historic facts, do it elsewhere.

We're looking at the sources you came up with.