I should note that I haven't had the best light for my trees over the winter prior to this year, and being near a window has been enough for them (ficus / bougainvilla primarily, previously, now I have some like pomegranate that I think are more sensitive). The trees have been fine. This is more of "trying to make it perfect" vs "trying to make it good enough", I wouldn't feel like you HAVE to get lights unless you have a particularly light sensitive species.
Based on what I'm seeing of your collection, nothing is giving me a vibe of "you're going to kill this without a light", so you may not NEED to do this. If it's a WANT thing, that's a different story. It'll help them grow better during the winter months, for sure, and maybe they won't shed as many leaves, but I doubt you'll kill them without it.
Wait til summer to root over rock the ficus. They seem virtually bomb proof from experiments I've done personally this year, but their STRENGTH will be much better to react to what you're doing in the summer, and you won't slow yourself down as much while waiting for it to recover.
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