There is no problem in this way, but how far can I lower this value to be more ideal and healthy, how can I measure this data?
As discussed in Memory Dangerously Low or Max Memory Too High, Brent Ozar recommends to allocate 4 GB or 10% of the total Memory, whichever is larger, to the machine itself as a starting point rule of thumb. This is to leave just enough Memory for the OS to breathe while maximizing the allocation to your SQL Server instance.
The SQL Server instance will utilize all of the Memory you allocate to it, as needed, to maximize performance. This is because it retains many things cached in Memory for future reference, such as the execution plans, the table statistics, and even the actual table data itself that was previously located off Disk. So you typically don't want to needlessly lower it.
I typically follow this rule of thumb myself, and have never had any issues.