Rubella is a viral infection which occurs once in a life time. IgG against Rubella only means your wife is immune to this virus (she either had the infection in childhood or was immunized against it) and not only is it not harmful to her future pregnancies it is virtually a guarantee that she will not get this infection during her next pregnancy. Rubella is harmful if, and only if, fresh infection occurs during pregnancy (especially early pregnancy) and since your wife already has positive IgG titres against rubella she cannot get this infection now. Therefore she will have no problems in subsequent pregnancies because of rubella.
Similarly CMV is also a viral infections and positive IgG titres are common in India as a result of infection in early life. Again, if IgG is positive you do not need to worry. Theoretically CMV can get reactivated in exceptional cases during pregnancy but it is so rare that you do not need to worry about it. Unless your wife is on long term steroids (during pregnancy) she does not have to be worried on that account either. Both Rubella and CMV IgG antibodies will be positive for years on end (practically all her life) so repeated titres are a waste of time and money. You should therefore stop getting these tests done again and again.
Both rubella and CMV can be harmful to individual pregnancy as indeed any viral infection but have no role to play in recurrent infections! so you do not need to worry about them anymore.
Most cases of two consecutive abortions are random events in nature and only an expression of reproductive waste. Reproductive wastage is inherent in the process of reproduction as nearly 70% embryos conceived are abnormal and they result in early abortions. In great majority of cases no cause is found so investigations after two abortions are not required. If your wife is healthy otherwise and has no chronic illness like diabetes, hypertension and renal disease, she does not need more tests. All the tests you have got done do not cause early abortions but now that you have got them done and they are normal you should stop worrying about that as well. No further tests are required as they will not contribute to her treatment or improve her chances of having a normal pregnancy.
Please have faith in nature and go ahead with the next pregnancy as soon as possible. She does not fit into the definition of recurrent abortion (which is three consecutive abortions) but for your knowledge and reassurance you can read the column on advice to couples with recurrent abortion as given on the Royal college of obstetricians and gynaecologists site at www.rcog.org.uk.
Vaginal infections need to be investigated and treated. Povidone iodine pessaries are often prescribed but have little effect. In fact in women who are allergic to it, this itself may be a cause for recurrent vaginal infection. Please get a wet smear made of vaginal discharge, and treat according to the diagnosis.
Occasional irregular periods are common but if they occur more commonly (more than three consecutive abnormal periods she would need medical evaluation to find the cause of such irregularity. I wish you all the best.