Fix various basics language strings

[gizmecano]

Fix various common language strings, such as:

• [x] fix article for métaélément (08b12adcd09a102c625e2a2f8a22d5885fb97fb4)
• [x] harmonize string for error_filetype (3791392ff09b89736705a1e1d1aebb6272dd6026)
• [x] set congruous wording for missing order identifier (2919956db06749272b2b748f3c8429c9c5cc0c78)
• [x] fix sketchy string for error_permission (61995a94a8c6dbaa29d9396671f1e2191e58def7)
• [x] harmonize string for error_cheque (2b81b0877925eef0d6b701871220ce39bc513962)
• [x] amend string for button_login (fbc97ff366e6f05022404762cac79a92865d1962)
• [x] amend some strings for text_login (14506f7dda309e1c726dd1f94b815c704495edf6)
• [x] fix string for text_confirm (d3f8f6cf45dd9c2bf646919cb1170b2436c50458)