The only way to keep the pace with ostheer curently (in my view) is to grenspam with as many lmg42 as you can get + 251, a pack + pzgrens with schrecks, get 1-2 PIVs then pump Tigers like hell - they are in pretty bad shape right now though.
Red all these walls of text in the thread, everybody is right in a way or another, but it's something wrong with this faction which can't be fixed just by an MG42 buff - which is necessary. I'd say in addition make teching cheaper from fuel point of view and do something with that crippled Tiger, or make units in T4 worthy of investment. Currently for late game what are your options as OST? An intangible T4 with units that you have to wonder if they really deserve to be built - Panthers are eaten alive by 85s IS2s and ISUs, pzwerfers are just Fireworks - and a Tiger call-in which, again, is eaten alive by the same soviet heavy call in mentioned before plus Jacksons. Ostheer used to own the late game and it's normal for a faction to own a moment in game that it should exploit the most. The problem with Ostheer is that it's not owning any moment in game in the current state, while all other factions are.
You can replace Ostheer with USF or Sov in your wall of text. Well and USF doesn't have any Call-in solution to skip their T4.
The only Faction that hasn't any significant downside is OKW today.
Ostheer is the most balanced faction imo, the only nerf they may received is around LMG stats, but this goes for all factions in a raw if Relic decide to touch this statistic.
In comparison OKW really need a huge nerf in many areas or a complete redesign (which will probably never occur), Sov and USF need some tweaks to balance their strength and weaknesses.