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Can you post a photo here?
Yes CFWA lighting can get challenging, feel free to move the strobes around, possibly tucked in right next to the dome, even angled slightly in. You’d then run them at very, very low power, and you’ll be surprised by how little backscatter you get (see our CFWA lesson here for examples: https://theunderwaterclub.com/courses/underwater-wide-angle-course/lessons/close-focus-wide-angle-cfwa/).
Your mini-flashes can suffice if the subject isn’t too big (basketball size would be my limit) and if you don’t care about lighting the surroundings smoothly.
To your other question, every lens I use for CFWA focuses right on the dome, but note the ‘mini focus distance’ spec is measured from the camera sensor. So if you get something like 14cm, it might end up being right on the lens glass.