Whenever I try to make multisyllabic words, it doesn’t turn out right. There should be a feature when you type a hyphen in between syllables (i.e., kit-ten), the syllables are separated to different notes. Or, if you want to extend a monosyllabic word to multiple notes (i.e., sli–me), it copies the last vowel phoneme onto the notes. Similar to Melody/Harmony Assistant’s “Virtual Singer” which was made THIRTEEN YEARS AGO. WAKE UP, DREAMTONICS!
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Use kitten / + for the first case and slime / - for the second.
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Yeah, it’s in the manual - just a different way of doing things but allows for +/- to be combined, like kitten - +.
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Yeah the + and - is what you need and are looking for.
They work a treat for exactly what you describe.
Be nice to Dreamtonics. They’re nice to us.
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While I’m aware of the existence of the + input, honestly it’s really unintuitive. I, and I think most people, would expect to be able to type a word and simply have each syllable automatically be split into notes. Or at the very least, to be able to use hyphens as OP suggests, especially considering the hyphen is the standard way of separating syllables in sheet music, for example. I agree an automatic syllabification function or using a hyphen between syllables instead of + after the whole word would be ideal.
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FYI, Yamaha has a patent of splitting syllable with hyphen.
And also has lots of interface patent about inputting lylics.
So, some of functions are impossible to implement for now or Kanru have to pay high patent fee and available, maybe.
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…Wow. I… literally don’t have words for this.
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Yamaha are pretty good at patenting all the useful things that other synths need and stifling the market when they don’t update their product frequently enough in the process. They have patents for lots of things that might seem like no-brainers 
I think this is a happy middleground as it allows for a note to be extended and then go to the next syllable, rather than just hyphens.
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Absolutely disgusting.
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While it’s being said there are patent issues which are not very likely to resolve on their own (besides waiting for the 20th year since filing date, which actually isn’t that much of a wait considering how long it’s already been around), what we can always do is to offer more options.
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Wow. I’M STUPID. I should look at the manual more often
As a side note, I’m not sure if you’re suggesting that extending a syllable isn’t possible in Vocaloid, but I’m pretty sure that’s what “-/” does.
What do I do if this topic isn’t needed anymore?
Leave it here for those who follow.