Underperforming means it needs buff.
You'd rather see the gun having lower scatter or reload and significantly increase one shot wipe potential or have MGs buffed to increase AI reliability that way?
In fact, I believe that T34 approach to MGs should be how AI is balanced for all generalist tanks.
Your claim that according to patch notes T-34/76 has "shit perfomance in its main gun" is simply false. That is actually your own personal opinion and if you want to back it up I suggested you provide a comparison of the guns of meduim tanks including AOE profiles, scatter and reload values or in game tests.
If you want to do so pls do it in another thread since this one is about Cromwell's mgs.
Now pls move on.
When it comes to Cromwell I would suggeset a redesing to a "flank tank" (for T-34/76 also) a unit with improved perfomance at close with higher penetration and reload at close range. I see litle reason why the main gun of most vehicles have the same reload at all ranges.