How to find a specific column name in table design view?
If you start by looking at the table definition in the Object Explorer and expand the columns properties, you can simply type the first letter of the column you are looking for.  If you keep hitting the same letter, SSMS will cycle through all the columns that start with that letter...   

if you then right click the column and and choose modify, it will open the designer at the right column...

(using ssms 17.9.1 - but worth a try)