I think levels.fyi is a bit off. Generally speaking, principal is a terminal level at Oracle so it takes some work to get to that level. We have some people with 20 yoe at principal level. So it is definitely not equivalent to Salesforce senior.
I think S lmts == O pmts, S pmts == O consultant mts. LMTS is a terminal level at Salesforce. I saw a couple of examples when S lmts went to O pmts, also S mts to O smts.
When people change job, they usually don't make lateral move. I am not sure what consultant mts is. In our org - you go from principal to sr principal (IC5) which is very selective. It is similar to tech lead type roles.
Same SMTS and vice versa is also same
How about Principal software engineer role of Oracle? Is it less or more than smts?
Salesforce inherited these titles from oracle only. SF CEO was former oracle employee. It is same.