I think this is all making it all too complicated. So let's make it even more complicated..

First of all, it is not about what the producers (programmers) want, it is about what the consumers (visitors) want. Thus you have to find the "thing" that works best for the consumer, not for the programmer. If you're smart you make the field "translatable", as in you can adapt its appearance by changing a setting in the admin panel (studio). Don't only limit it to words but also images, see more so you can use a thumbs up/down image if you want / need.

The main thing is not to think to big / not to over think it.
Let's face it, "Like" might not be used in the proper way (as in grammar), it might be hard to translate.. but .. somehow 500million people know how to use it, and don't mind using it.

Even if you think about your "+OK" we can over think it and ruin the concept:
"OK" in various countries means alright / average.. nothing special.
Back home in the Netherlands you can also use it to curse somebody out by referring to ovarian cancer.

Does it mean you shouldn't use it now? No

Another solution that people posted on here is the "thumbs up/ thumbs down" .. now lets over think that.
Thumbs up is good in America..
Thumbs up" traditionally translates as the foulest of gesticular insults in some Middle Eastern countries — the most straightforward interpretation is 'Up yours, pal!'[ (also in parts of Africa)
In Bangladesh, Iran it is traditionally an obscene gesture, equivalent to the use of the middle finger in the Western world.
In the UK, specifically north-west England, a single-handed thumbs up sign can be used as a farewell or greetings gesture between young males.
In Japanese sign language, the thumbs-up indicates a man, or male gender as opposed to an extended pinky indicating female.
In India, although the gesture is well accepted, similar gestures have negative connotations..

Does this mean you can't use it? No

Another solution might be a simple plus or minus sign.
However same goes for here, other countries and cultures other meanings

Does this mean you can't use it? No

You shouldn't over think the concept. It doesn't matter if it isn't perfect English or if it isn't English at all. (Was Twitter / Facebook / Google a word before their launch??)
It does matter, however, how users perceive and see it; how they feel about it.
The whole point of these buttons is for users to show that they appreciate the work posted; which can be a blog post / a video / a picture etc.. All it comes down to is expressing the following conversation in one or two words (or signs): (Person 1) "Hey!, I went to the zoo yesterday and I saw this gorilla banging on the window, isn't this a sweet picture!" (Person 2) "O wow that is so cool / I like that / I hate that / so interesting/ so nice etc"