Any alternatives for the word "deservability"?

I think worthy or worthiness is the perfect substitution word you're looking for. It is used to indicate that someone has earned the value attributed them through their proven record or high quality of work and effort.

Miriam-Webster defines it as: worthy

  : good and deserving respect, praise, or attention
  : having enough good qualities to be considered important, useful, etc.

You deserve that job. But sometimes, capability is also required along with worthiness.

I think it's fine as is. I was an English major and there are some philosophical questions in regards to the English language in particular. In general there are two schools: it's only valid if it's in the dictionary, or it's valid if people use it and understand it. This can almost be defined as the Webster's vs American Heritage approach. The English language, especially American English, in my opinion is strong exactly because it allows such flexibility. Some other languages don't. At the end of the day I think any reasonable English speaker will understand exactly what you mean and agree with the spelling. I think deservability in particular is a very clear word choice because the combination of "deserve" and "ability" which is not expressed in any other alternative. Anyway, I hope that helps.