Why would you build a Romanian complex as Germany? The ONLY time where it would be beneficial to build one would be on G1, and you need to build a CV and naval units on that turn anyway to threaten England.
Scenario One
G1
Buy major IC
R1
Russia builds at least 10 land units
G2
Buy 10 INF/ART for Romania
R2
Russia builds at least 10 land units
G3
Buy more land units, usually blitzing units, Barbarossa
R3
Russia builds at least 10 land units
Scenario Two
G1
Germany builds 1 CV 1 SS 1 DD
R1
Russia builds land…
G2
Germany builds major IC in Romania, land units
R2
Russia builds land…
G3
Germany builds INF/ART in Romania, Barbarossa
R3
Russia builds…
OR
Scenario Three
G1, naval, G2, ART, G3 ART/INF or MECH/ARM - should be able to build at least 30 land units between G2’s $70 and G3’s $50. Germany still has unit advantage against the Soviets, also is able to threaten Sealion with G1 buy and force UK to spend on INF for several turns. Massive stack of INF and ART from G2 buy should be ready to go for G4 Barbarossa, much the same as if you’d built the IC on G2. G1 major IC build is slightly faster, but also has less options at beginning of game and UK won’t play so defensively.
Effectively you’re losing an entire turns worth of build by purchasing the major IC in the first place, either on the first turn or the second turn. If you build it on the second turn you have even MORE of a future land unit deficit in comparison to Russia’s builds (-20 potential land units to their +20). I could possibly see the need for the major IC with the OOB or Alpha +.1 setup with the starting minor IC in Berlin, but with 20 total production in Alpha +.2 its unnecessary.
Best bang for your buck is all ART on G2. Follow that up with stacks of MECH/ARM to keep the initial wave’s momentum going all the way through Moscow on G8.