From what I understood about your situation, this is not an easy task for Robot. However, there is a rather simple way to handle this by having a universal test script and case-specific excel file.
- Populate your excel spreadsheet with
FieldName
and TabName
to be able to locate the input on the page. My way of doing this would be:

Retrieve TabName, FieldName and Value to a list using ExcelLibrary (you seem more familiar than me with the use of it, so I leave it up to you). As a result of this step you will have a list of 3 items, say ${SingleFieldOfSingleUser} # ['Tab1', 'Field1', 'aaa']
Now create a list of these Fields:
\ Insert Into List ${SingleUser} ${ColIndex} ${SingleFieldOfSingleUser}
Instead of manually going through every possible Input Field, use a universal custom keyword:
:FOR ${UserAttribute} IN @{SingleUser}
\ Input Attribute Into User Form ${UserAttribute}
The keyword might look something like this:
Input Attribute Into User Form
[Arguments] ${Attribute}
# Try switching to the correct Tab. If already there, don't break upon error
Run Keyword And Ignore Error Click Element ${Attribute[0]}
# Input Value
Input Text ${Attribute[1]} ${Attribute[2]}
Profit! You can now provide an Excel spreadsheet with any number of columns depending on which fields you want to update.
Here I leave for you a mockup of complete code listing:
*** Keywords ***
(...)
Read Column Data For User
${SingleUser} Create List
:FOR ${ColIndex} IN RANGE ${COLCOUNT}
( ... Excel-related code here ... )
\ ${SingleFieldOfSingleUser} Create List ${TabName} ${FieldName} ${Value}
\ Insert Into List ${SingleUser} ${ColIndex} ${SingleFieldOfSingleUser}
:FOR ${UserAttribute} IN @{SingleUser}
\ Input Attribute Into User Form ${UserAttribute}
(...)
Input Attribute Into User Form
[Arguments] ${Attribute}
Run Keyword And Ignore Error Click Element ${Attribute[0]}
Input Text ${Attribute[1]} ${Attribute[2]}
P. s. you really don't need so many FOR loops and lists to make this thing work, but I tried to make my solution as close to your original coding pattern as possible in case it has some hidden personal value.