I have 3 suggestions for improving mines regarding production methods. Techniques and shaft Infrastructure for mines. just because a mine is using the latest technology doesn't mean it is using the latest techniques or is providing safe, quick transporation for miners.

Techniques would be split into two groups, Sluicing and Mine Structure, Sluicing is an ancient technique using natural water flow to sift through dirt and stone for ores and transporting them, the next sluicing method would be hydraulic mining using powerful water jets, and finally power sluicing is the modern technique and is basically a motorized water conveyer. Sluicing can only be used for materials like Coal, Lead, Gold, Copper, Common ores, and Advanced ores. i would recommend a -50% bonus to common/advanced ores to account for differing mineral densities making sluicing impossible. This production method would cost basic construction materials and water

Mine structure is basically the general structure of the mine such as open quarries, mountaintop removal, and strip mining. these are more modern methods being increasingly used past the 1950's and 1960's these would only provide throughput at the cost of organizational goods like data and telecommunications, and can later be expanded through gps excavation

For mining infrastructure think of pillar-mining, mineshafts, and elevators which would improve throughput at the cost of wood, steel, tools alloys or other goods needed for construction.

the best and easiest idea would be to add more explosives production methods like gelignite, and ammonium nitrate fuel oil (ANFO). Being produced in the 1880's and 1960's respectively, gelignite would only be slightly safer and easier to use than dynamite, but ANFO would be even easier to use, safer, and affordable as oil drilling became more common (A possible requirement). therefore while outputs would only increase by 5-10 ores, inputs would be less or the same and could even have less workers.

Hope you like my suggestions! if i had to choose one to cut it would be sluicing as sluicing could be instead used as the first level of mining infrastructure (and not be present for the mines i said above)

This may not be exactly what you are talking about, but the base game resources are way out of proportion compared to the ones you have added.

The coal, wood, iron and arable land are all weirdly allocated for a game running till the 2000s. I know specially Australia is heavily underrepresented with the amount of mines given. Australia is the number 1 producer in the world of lead, iron ore and gold.
https://en.wikipedia.org/wiki/Mining_in_Australia#Statistical_chart_of_Australia's_major_mineral_resources
This is represented in game by the entirety of Australia having less coal and iron than 2 English states.

I'd just suggest going through world countries and finding out how much they produce of each goods and then increasing world's supply accordingly. I'd be down to get some of those numbers if you'd use them.

Integrating something similar to this mod but for all resources you've added + base game ones would really help with the issue:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3459869359