The problem is that in French language the decimal number is expected with "," instead of "."

In this case I would add some validations not allowing the user to enter these values based on if the decimal field takes a "," or a "." or you can do some type of manipulation of the decimal that the user enters based on if the user is French or English.

Hello Ramesh, We can do this using substitute function on basis of user locale
ex.
a!textField(
label: "Lorem Ipsum",
labelPosition: "ABOVE",
value:if(userlocale(loggedInUser())="fr_CA",if(rule!EBS_Utils_checkIsNull(ri!data),{},substitute(ri!data,".",",")),ri!data),
saveInto: {
a!save(ri!data,if(userlocale(loggedInUser())="fr_CA",todecimal(substitute(save!value,",",".")),save!value))
},
refreshAfter: "UNFOCUS",
validations: {}
)

Here ri!data is the number(decimal) type field

This is the idea I had in SAIL but rameshm0001 is using a Portal form.

Both these userlocale() and loggedInUser() functions are available in older appian as well, you could use them in output tab of portal form and modify the input accordingly.