I have been using Gtranslate to offer regional language services on Kiku and thus far, I’ve liked it the best. Weglot was nice but expensive as hell. The best thing about Gtranslate imho is that it offers in-browser editing which makes the entire ordeal a little more palatable.
Frankly speaking, I don’t really know the quality of translations coming out of web translators. The out-of-context translations seem weird and thus the need for a native speaking Japanese translator to cross check the Japanese the translation machine spits out. As such, I’ve considered making all of Kiku in Japanese to begin with but unfortunately the payment processors and other plugins I use only have English support which messes things up quite a bit.
So as of right now, the only reason Gtranslate is useful with Kiku is not because of the translations, but because it allows us to do in-browser editing for text that would normally be inaccessible to us with code. I just wish I didn’t have to pay 9$ USD a month for this, considering the spottiness of the translation output.