Point 79 in the category of PAST is defined as:
past perfect simple, IMAGINED PAST, the affirmative form after ‘if only’, and the affirmative and negative forms after ‘wish’ to talk about regret.
This is a rare match of grammar levels with Pearons’ GSE 62 B2:
If only I’d worked harder.
I wish we’d bought that house.
if only * _vhd _vvn
1 IF ONLY I HAD KNOWN 293
2 IF ONLY WE HAD KNOWN 62
3 IF ONLY I HAD THOUGHT 42
4 IF ONLY THEY HAD KNOWN 39
5 IF ONLY I HAD READ 35
IF ONLY SOMEONE HAD TOLD
BBC News7 IF ONLY I HAD FOUND 32
8 IF ONLY HE HAD KNOWN 31
9 IF ONLY I HAD LISTENED 30
10 IF ONLY I HAD TAKEN 28
11 IF ONLY WE HAD DIED 24
12 IF ONLY YOU HAD KNOWN 23
13 IF ONLY SHE HAD KNOWN 22
14 IF ONLY THEY HAD LISTENED 22
15 IF ONLY I HAD GONE 18
16 IF ONLY I HAD SEEN 18
17 IF ONLY THEY HAD KEPT 17
18 IF ONLY I HAD BOUGHT 14
19 IF ONLY I HAD GOTTEN 14
20 IF ONLY I HAD PAID 13
wish * _vhd _vvn
1 WISH I HAD KNOWN 3332
2 WISH I HAD FOUND 1441
3 WISH I HAD READ 1316
4 WISH I HAD SEEN 1057
5 WISH I HAD BOUGHT 1033
6 WISH I HAD TAKEN 985
7 WISH I HAD THOUGHT 795
8 WISH I HAD GOTTEN 690
9 WISH I HAD GONE 535
10 WISH SOMEONE HAD TOLD 527
11 WISH I HAD STARTED 495
12 WISH I HAD KEPT 392
13 WISH I HAD ORDERED 353
14 WISH I HAD MADE 323
WISH I HAD DISCOVERED
HONOLULU Magazine16 WISH YOU HAD KNOWN 296
17 WISH I HAD LEARNED 274
18 WISH I HAD USED 266
19 WISH I HAD PURCHASED 250
20 WISH I HAD TRIED 240
wish * _vhd _xx _vvn
1 WISH I HAD N’T WAITED 78
2 WISH I HAD N’T BOTHERED 57
3 WISH I HAD N’T BOUGHT 56
4 WISH I HAD N’T SEEN 48
5 WISH IT HAD N’T HAPPENED 40
WISH I HADN’T WASTED
Metro7 WISH I HAD N’T READ 34
8 WISH I HAD N’T SAID 28
9 WISH IT HAD N’T TAKEN 28
10 WISH I HAD N’T SOLD 26
11 WISH I HAD N’T SPENT 26
12 WISH I HAD NOT WAITED 26
13 WISH I HAD N’T TAKEN 25
14 WISH I HAD N’T GONE 22
15 WISH YOU HAD N’T SAID 20
16 WISH I HAD NOT BOUGHT 19
17 WISH I HAD N’T GOTTEN 18
18 WISH THEY HAD N’T GONE 18
19 WISH YOU HAD N’T ASKED 18
20 WISH I HAD NOT PURCHASED 16