I think the Main Stand was originally six years as mentioned here - Main Stand - "It made sense business wise for FSG to borrow the money with Liverpool saving around £3million per year [in interest]over the six years it will take to pay back the loan." but that may have changed due to Covid hitting the match day revenues.
I've not seen any loan mentioned for the Training ground, I'm sure I saw somewhere it was coming out existing funds and the only thing I've found for the Anfield Road end is just that it's a commercial loan rather than going through FSG - https://www.liverpoolecho.co.uk/sport/football/football-news/fsg-liverpool-cost-anfield-road-17331567