Welcome to the Airtable community!
Is this what you want?

RegEx can be tricky to craft. Your expression wasn’t working because the formula was looking for the exact string in {Del}. However, you want to look for any word in {Del} which requires a different approach. In this formula I use a RegEx to convert the contents of {Del} to a RegEx expression that looks for any of the individual words in {Del}, then applied that RegEx expression to {Concat}. I also threw in a little additional handing of spaces for good measure.
IF(
{Del},
TRIM(
REGEX_REPLACE(
{Concat},
CONCATENATE(
"(",
REGEX_REPLACE(
TRIM({Del}),
" +",
" *)|("
),
" *)"
),
""
)
),
{Concat}
)
Welcome to the Airtable community!
Is this what you want?

RegEx can be tricky to craft. Your expression wasn’t working because the formula was looking for the exact string in {Del}. However, you want to look for any word in {Del} which requires a different approach. In this formula I use a RegEx to convert the contents of {Del} to a RegEx expression that looks for any of the individual words in {Del}, then applied that RegEx expression to {Concat}. I also threw in a little additional handing of spaces for good measure.
IF(
{Del},
TRIM(
REGEX_REPLACE(
{Concat},
CONCATENATE(
"(",
REGEX_REPLACE(
TRIM({Del}),
" +",
" *)|("
),
" *)"
),
""
)
),
{Concat}
)
Hello,
Thanks for your welcome !
And thanks for the answer. I would never have found! It’s work perfectly !
Thanks again !