Well, you are partially correct, the issue was opacity, but "term" is not completely synonomos to "word". The capitalized terms are common english words, but retasked as proper nouns.
I get what you're saying (I think) because I'm doing the same thing in one of my WIPs. Specifically a group of characters have a metaphysical concept called the "Road," which I capitalize to make sure the reader distinguishes it from
a road. And I'm pretty happy with my choice of capitalizing it.
However, it gets a bit fuzzy when I consider other words that the characters use, which have a particular meaning as specialized terms within that group. I can say "I had a guide lead me through the mountains," but when they say "guide" the word has a particular meaning within their group. So should I capitalize it so readers understand I'm referring to that particular thing? Should the council of elderly members that advises the group be referred to as the elders or the Elders? Etc. Etc. I have not found a satisfactory answer to this, but I welcome opinions.
Liosse, if your beta readers are complaining that the terms as you're using them are opaque, that may be less an issue of capitalization and more an issue of defining these terms so the readers understand. But without a specific example, I'm not sure if I can give better advice than that.