Complex Query with Sharepoint Tables

Greetings! This is my first post here; hitting a snag with modeling my data and getting it into something that is helpful to decision-making. 

In my company, each of our positions require one or more certifications. What I want to do is build several reports to help understand which employees are on track to getting certified or are within 30-60-90 days of being fired for not achieving certification. 

Five total tables. Each table stored in SharePoint lists. 

1. WB Manpower - list all company positions and the date the position was filled
2. WB Personnel - lists all people
3. SPeD Certifications - lists all available SPeD certifications
4. WB Personnel SPeD Certs - lists a record for each SPeD certification a person earns and the date they earned it. Look-up to "WB Personnel' and "SPeD Certifications".
5. WB SPeD Requirements - lists the SPeD Certifications required for each position. Look-up to "WB Manpower" and "SPeD Certificaitons" 

The fact I am re-using the "SPeD Certificaitons table seemed to be causing me issues. Being a somewhat novice to Power BI and I had to call it quits and come here for help!! 

The attached photo shows my data structure in detail. 

Would like to build a visuals which help the reader understand the state of the certification program. Some ideas include (open to other smart peoples inputs here!!)

: 
- % of Personnel Certified/not certified

- Lists of people coming due in next 30-60-90 days