Demo charges do not need any fixes, because they are not broken in any way.
If you want to fix call-in meta, make tier units appealing, this goes specifically for soviets as all other armies have reliable tier units, only soviets needs to rely on doctrines for armor and infantry.
Doesn't change the fact that you can and many times benefit on skipping all teching so you can pump out the more cost efficient callin units instead. Demo charges need fixing but everyone knows you are a soviet fanboy so i don't count on ever making you understand.