Load big file in MySQL table
The data in a CSV file is encoded one way; the table in MySQL is encoded another way.  The difference could be 2x either way.  That is, the 25GB csv file might, for example, expand to 50GB, then have trouble adding on the indexes.

When MySQL runs out of disk space, it waits for you to free some space.  This might explain 40 hours.  Or it dies.

Does one of you have SSDs, the other have HDDs?

What was the value of key_buffer_size when using MyISAM?  Keep in mind that innodb_buffer_pool_size and key_buffer_size are competing for RAM, so you should be careful when switching between engines.

InnoDB wants a PRIMARY KEY; you don't have one.

How big is the TEXT column typically?  InnoDB stores them off-record in some situations.

When did things go sour?  During the LOAD?  Or during the CREATE INDEX?

When adding an index to a MyISAM table, it will either "repair via key buffer" or "repair by copying" (or something like that).  The clue is visible in SHOW PROCESSLIST during the CREATE INDEX.  If it is by "key_buffer", then 8M is much too small.  1G may be suitable for your machine.  If it is the other one, then I am surprised that it took so long.

Another trick (depending on the indexes you have or will have) is to first sort the data by the main key (field3? in your case) before doing the LOAD DATA.

If field1 is always 12 characters or fewer, then declare it VARCHAR(12).  (If it might get a bit bigger, pick some other limit.)  TEXT has some drawbacks compared to VARCHAR.  I am not sure whether it is relevant for this case, but it should not hurt.