I don't have so much knowladge about the biological and physiological composition of Musa species. But ı can say, you can try zeatin concentration (0.25, 0.5, 1.0, 2.0 and 4.0 mg/L) with IBA concentration (0.1, 0.2 and 0.3 mg/L). If you dont have any good results you have to modify the medium ingredient especially amounts of Ca and Mg
here i have enclosed an article for your reference. I hope its very useful to you unfortunately the images not displayed but experimental field might be useful to you. All the best.
If you are only interested in multiplying the plantlets from sucker stages, try using MS based medium supplemented with benzyl-aminopurine (BAP) in the ranges 0.5 - 5mg/L of medium.
Good luck!
Article Stability of micropropagated Musa acuminata cv. Grand Naine ...
try to supplement your current media formulation (that have PGRs) with about 20 - 100ng/L of polyamine (putrescine) in the media. this is likely to enhance multiplication at all stage