Thanks.
This goes to show why I am not convinced that L-159 or L-39 is needed. Both K-8 & L-159 seem to have similar flight performance based on the air-frame.
A trainer having FBW can be tailored to mimic another combat plane's performance. This could be the only reason for PAF to go for another platform.
The L-159 is between the K-8 and JF-17.
For example, the L-159 uses an afterburning engine with a thrust-rating of 28.2 kN, while the K-8 uses a non-afterburning engine with 16 kN thrust. If one's going to acquire the L-159, it'd for the FCU/LIFT role after the K-8, which is currently being done with FT-7Ps. It'll depend greatly on how much cheaper the L-159 is compared to the JF-17 in terms of acquisition and operating cost, especially the latter.
This is empty speculation on my part, but other reasons why the PAF might be considering the L-159:
(1) reduced confidence in the F-7PG/FT-7PG for post-2020 usage, especially in the training roles. There have been some noticeable losses in recent years with that aircraft;
(2) a need for a slow ground-attack aircraft for COIN, the L-159's payload is more than double than that of the K-8. Another option is turboprop planes, but the PAF doesn't seem to like those for the ground-attack role.
(3) the JF-17 might not be cheap enough for the training role, esp. after PAC transitions to the Block-III. Instead of maintaining a fleet of trimmed down JF-17s which can't do much in war, the PAF may prefer dedicating all JF-17 induction and use to purely frontline units, leaving advanced training to a separate and non-critical platform.
(4) leveraging for other Czech equipment, e.g. passive ELINT sensors (i.e. VERA), CZ small arms (i.e. unrestricted licenses for third-party exports), etc.