A couple of things to consider.

Short’s Law #1: You cannot automate that which you don’t do well manually.
In this case, you state you don’t have a corporate solution for K capture and re-use, and your org is interested in a software solution for same. You then state that the current approach on spreadsheets is deficient in several ways. Suggestion: challenge work teams or departments to figure out how to improve K sharing and leveraging lessons learned. Make it a competition. Until you crack this one, you don’t have anything to automate. A new software solution for K sharing will just get in the way.

Short’s Law # 2: Proposed changes should be cognitively consistent and culturally compatible.
Carefully review the deployed software, processes, procedures, norms, etc. already in use. What is already present? How is it used? What additional capabilities does it have that is not being used; or is being used, but not for K sharing?
There is no “KM in a Box” solution. KM and K Sharing are a melange of tools and behaviors and processes and policies, so the way one org does it will likely be unique to that org in ways that will make it difficult to “drag and drop” into another one. Your best bet is to leverage what you are already using; the behaviors and norms that are already in place; the tool sets that employees are already familiar with. You can build on these by creatively augmenting what people are already using; and not requiring them to do something they lack the skill or knowledge to do (cognitively consistent); and by not transgressing established behavioral or cultural norms (culturally compatible).